Vivo X300 Pro VS Xiaomi 15 Ultra

In terms of overall footprint, these two phones are nearly twins — almost identical height (~161 mm) and width (~75.3–75.5 mm). Where they diverge meaningfully is in thickness and volume. The Vivo X300 Pro measures just 8 mm thick, while the Xiaomi 15 Ultra is noticeably chunkier at 9.4 mm — a 1.4 mm difference that is quite perceptible in-hand and in-pocket. This directly translates to the volume gap: 97.4 cm³ for the X300 Pro versus 114.2 cm³ for the 15 Ultra, meaning the Xiaomi displaces roughly 17% more space despite having essentially the same screen-area footprint. Weight is nearly a wash at 226 g versus 229 g, so neither has a meaningful ergonomic edge there.

On water resistance, both carry a Waterproof rating, but the certifications differ. The X300 Pro holds an IP69 rating, while the 15 Ultra is rated IP68. IP68 covers sustained submersion in still water, which is sufficient for everyday splashes and accidental drops in water. IP69 goes further, adding resistance to high-pressure, high-temperature water jets — a meaningful step up for users who might rinse their device under a tap or use it in more demanding wet environments. Neither phone has a rugged build or a foldable form factor.

The Vivo X300 Pro holds a clear design advantage here on two fronts: it is substantially slimmer and more compact in volume, making it the more pocketable and premium-feeling device physically, and its IP69 certification offers a higher tier of water protection than the 15 Ultra's IP68. For users who prioritize a sleek profile or need more robust water resistance, the X300 Pro is the stronger choice in this category.

Both phones use OLED/AMOLED panels with identical 120Hz refresh rates, 300Hz touch sampling, and full support for HDR10+, Dolby Vision, and Always-On Display — so the baseline experience is equally strong. The real story is in resolution and sharpness. Despite being slightly larger at 6.78″, the Vivo X300 Pro renders at 1260 x 2800 px, yielding 452 ppi. The Xiaomi 15 Ultra packs a 1440 x 3200 px resolution into a marginally smaller 6.73″ panel, pushing pixel density to 522 ppi — a 70 ppi gap that is genuinely visible when reading small text, viewing detailed photos, or using VR-adjacent applications. At typical viewing distances the X300 Pro is perfectly sharp, but the 15 Ultra's screen is objectively more refined.

One point swings back to the X300 Pro: it features branded damage-resistant glass, while the Xiaomi 15 Ultra notably does not list any such protection. In day-to-day use, this matters — scratch and impact resistance from a certified glass layer reduces the risk of display damage from keys, drops onto hard surfaces, and general wear, potentially saving costly repairs over the device's lifetime.

On balance, the Xiaomi 15 Ultra holds the display edge for users who prioritize pure visual fidelity — its higher resolution and pixel density are a measurable, real-world advantage. However, the Vivo X300 Pro counters with damage-resistant glass, making it the more durable choice for those who value longevity over peak sharpness. Which wins depends on the user's priorities, but for display quality alone, the 15 Ultra leads.

Both the Vivo X300 Pro and the Xiaomi 15 Ultra come with 1024GB of internal storage and 16GB of RAM. The Vivo X300 Pro is powered by the MediaTek Dimensity 9500 chipset, while the Xiaomi 15 Ultra features the Qualcomm Snapdragon 8 Elite chipset. Both phones use 3 nm semiconductor technology and support 64-bit architecture, with integrated LTE and integrated graphics.

When it comes to benchmark scores, the Vivo X300 Pro scores higher on AnTuTu with 3,015,900, compared to the Xiaomi 15 Ultra’s 2,746,580. In Geekbench 6, the Vivo X300 Pro also leads in both multi-core (12,189 vs 10,059) and single-core (3,781 vs 3,234) scores.

The Vivo X300 Pro has a GPU clock speed of 1750 MHz, with 128 shading units, while the Xiaomi 15 Ultra’s GPU clock speed is 1100 MHz, but it has a significantly higher number of shading units at 1,536. Both devices feature RAM speeds of 5333 MHz (Vivo X300 Pro) and 5300 MHz (Xiaomi 15 Ultra), and both support DDR5 memory. Other performance-related specs such as maximum memory bandwidth (85.3 GB/s for Vivo X300 Pro vs 85.1 GB/s for Xiaomi 15 Ultra), L3 cache (16 MB for Vivo X300 Pro vs 8 MB for Xiaomi 15 Ultra), and multithreading are the same on both phones.

The rear camera systems tell a clear story of depth versus breadth. The Vivo X300 Pro fields a triple-lens array headlined by a 200 MP main sensor, while the Xiaomi 15 Ultra adds a fourth lens to its own 200 MP setup — giving it an extra focal length for more compositional versatility. More practically, the 15 Ultra pulls ahead on optical zoom at 4.3x versus 3.7x on the X300 Pro. That gap becomes meaningful in real-world telephoto shooting: the extra reach translates to noticeably tighter framing on distant subjects without any digital degradation. Both phones share OIS, phase-detection and laser autofocus, RAW capture, and identical 4320p at 30fps video ceilings, so the fundamentals are evenly matched.

Where the 15 Ultra further separates itself is in video and manual control. It supports HDR10 and Dolby Vision recording — formats that preserve far more dynamic range and color volume in footage — while the X300 Pro offers neither. The 15 Ultra also adds manual shutter speed control, a feature the X300 Pro omits, which matters for photographers who want full creative control over motion blur in low light. The X300 Pro counters in one area: its front camera resolves at 50 MP compared to the 15 Ultra's 32 MP, a meaningful advantage for selfie sharpness and cropping flexibility.

Taken together, the Xiaomi 15 Ultra holds a clear overall camera advantage — more lenses, greater optical zoom, superior video recording standards, and fuller manual control. The Vivo X300 Pro reclaims ground only with its higher-resolution front camera, making it the stronger pick for selfie-focused users. For versatility across photography and videography as a whole, however, the 15 Ultra leads this category.

The software comparison between these two phones is remarkably tight — virtually every feature in this category is shared identically, from privacy controls and dynamic theming to split-screen multitasking, offline voice recognition, and widget support. The one version gap that matters, however, is significant: the Vivo X300 Pro ships with Android 16 while the Xiaomi 15 Ultra runs Android 15. A newer OS version means access to the latest platform-level security patches, privacy enhancements, and system optimizations from the outset — users on the X300 Pro start on a more current software foundation.

Flipping that dynamic, the Xiaomi 15 Ultra includes focus modes — a feature the X300 Pro omits. Focus modes allow users to define distinct behavioral profiles for work, sleep, or personal time, automatically silencing distracting apps and notifications on a schedule. It is a genuinely useful productivity and wellness tool that the X300 Pro simply does not offer within this spec set.

Neither phone gets direct OS updates, so long-term software support depends on each manufacturer's own update cadence rather than guaranteed platform commitments. On balance, the two products are nearly matched, but the Vivo X300 Pro holds a slight edge by virtue of launching on a newer Android version, even as the Xiaomi 15 Ultra counters with the practical addition of focus modes. Users who prioritize being on the latest OS version will prefer the X300 Pro; those who value structured digital wellbeing features will lean toward the 15 Ultra.

Capacity is where the Vivo X300 Pro makes its most decisive statement in this category. Its 6510 mAh battery holds a meaningful 510 mAh advantage over the Xiaomi 15 Ultra's 6000 mAh cell — roughly an 8.5% larger reservoir. In practical terms, that margin can translate to an additional hour or more of screen-on time during heavy use, and a noticeably more comfortable buffer on long travel days without access to a charger. Both are large batteries by any measure, but the X300 Pro's edge is real and consistent.

Wired charging is a dead heat — both top out at 90W, meaning similar times from empty to full when plugged in. Wireless charging is where the pendulum swings back toward the Xiaomi 15 Ultra: its 80W wireless speed is double the X300 Pro's 40W. For users who rely on wireless pads as their primary charging method, this is a substantial convenience advantage — the 15 Ultra can replenish much faster without a cable, narrowing the real-world impact of its smaller battery.

Both phones support reverse wireless charging and include a charger in the box, so neither has an edge on those fronts. The verdict ultimately comes down to usage habits: the Vivo X300 Pro is the stronger choice for users who prioritize raw endurance and primarily charge via cable, while the Xiaomi 15 Ultra better serves those who live on wireless charging pads and can accept a slightly smaller battery in exchange for dramatically faster cordless top-ups.

Wired audio is off the table for both — neither phone includes a 3.5mm headphone jack, so wireless listening is the primary path. Both deliver stereo speakers and support aptX and aptX HD, covering solid Bluetooth audio quality for the majority of wireless headphones on the market. Beyond that shared foundation, however, the Xiaomi 15 Ultra pulls considerably further ahead.

The 15 Ultra adds LDAC, aptX Adaptive, and aptX Lossless — three codecs the X300 Pro entirely lacks. Each matters for different reasons: LDAC transmits up to three times more data than standard SBC, making it the go-to codec for Sony and other high-res wireless headphones. aptX Adaptive dynamically scales bitrate for stability and low latency, benefiting both music and gaming. aptX Lossless, the most demanding of the three, enables genuinely CD-quality wireless audio when paired with compatible hardware. Together, they make the 15 Ultra a meaningfully more capable platform for audiophiles or anyone invested in a premium wireless headphone ecosystem.

The Xiaomi 15 Ultra wins this category outright. The Vivo X300 Pro covers the basics competently, but the 15 Ultra's broader codec support — particularly LDAC and aptX Adaptive — gives it a substantial advantage for high-fidelity wireless audio that the X300 Pro simply cannot match.

At the core connectivity level, these two phones are essentially identical — both carry Bluetooth 6, USB 3.2 Type-C, 5G, NFC, dual SIM, satellite emergency SOS, and an infrared sensor. The sensor suite also mirrors each other closely, with GPS, Galileo, gyroscope, accelerometer, and compass present on both. Given how competitive flagship connectivity has become, this near-parity is expected, but the shared feature set is genuinely comprehensive.

The meaningful differences are few but worth noting. The Xiaomi 15 Ultra extends its Wi-Fi stack with Wi-Fi 6E support alongside the standard Wi-Fi 4/5/6/7 that the X300 Pro already covers. Wi-Fi 6E opens access to the less congested 6GHz band, which can deliver lower latency and more consistent speeds in dense wireless environments like offices or apartments with many competing networks. On the flip side, the Vivo X300 Pro lists a marginally higher peak download speed of 10,700 Mbits/s versus the 15 Ultra's 10,000 Mbits/s — a difference unlikely to be felt in real-world conditions but technically in the X300 Pro's favor. The 15 Ultra also includes a barometer, absent on the X300 Pro, which enables more accurate altitude readings and can improve GPS precision in navigation scenarios.

This category is closely contested, but the Xiaomi 15 Ultra holds a slim overall edge — Wi-Fi 6E support in crowded environments and the addition of a barometer are both genuinely useful inclusions that the X300 Pro lacks. Neither advantage is transformative for average users, but for those who care about network resilience or precise location data, the 15 Ultra is the more capable device here.

The miscellaneous spec set for these two phones is an exact match across every data point provided. Both include a video light, and neither features sapphire glass, a curved display, or an e-paper secondary panel. There is simply no differentiator to analyze here.

This category is a complete tie — the Vivo X300 Pro and Xiaomi 15 Ultra are indistinguishable based on the available data, and neither holds any advantage over the other.