Nokia Lumia 635 review
Processor: Quad-core 1.2GHz Qualcomm Snapdragon 400, Screen size: 4.5in, Screen resolution: 480x854, Rear camera: 5-megapixel, Storage: 8GB, Wireless data: 4G, 3G, Size: 129x66x9.2mm, Weight: 134g, Operating system: Windows Phone 8.1
The Nokia Lumia 635 is the 4G version of the Lumia 630. It may not seem like it at first, as both phones look almost exactly the same. Both have a 4.5in screen with a 480x854 resolution, a quad-core 1.2GHz Qualcomm Snapdragon 400 processor, a rear 5-megapixel camera, and both run Windows Phone 8.1. The key cosmetic difference lies in the Lumia 635's glossy outer shell, which helps distinguish it from its cheaper matt cousin.
However, the Lumia 635 isn't simply a 4G carbon copy of the Lumia 630 with a different case, as our tests revealed a few crucial variations between each handset.
The biggest difference was the quality and brightness of the screen. While the Lumia 630's peak brightness measured 318.74cd/m2, the Lumia 635 measured much higher at 380.79cd.m2. It doesn't seem like a huge jump on paper, but when we held each phone side by side, our test images were noticeably brighter on the Lumia 635. This meant colours had a bit more punch and whites looked much cleaner. The Lumia 630, by comparison, had cooler whites that were tinged with blue. On the upside, the Lumia 630's lower brightness level did mean that blacks were slightly deeper, measuring 0.35cd/m2 as opposed to 0.47cd/m2 on the Lumia 635.
The Lumia 630's screen also produced more accurate colours, as our colour calibrator showed it was displaying 85 per cent of the sRGB colour gamut. The Lumia 635, on the other hand, was only showing 83 per cent. This is still good for a budget phone, but our colour gamuts revealed the Lumia 635's main area of weakness was its blues and cyans. Magenta was slightly stronger, though, and we could see this difference onscreen, as colours looked a fraction more purple on the Lumia 635 than they did on the Lumia 630. It's a very small difference, though, and one that can be easily adjusted using the Display options in the main Settings menu. Our results were based off each phone's default settings, but the advanced colour profile, for example, gives you control over the colour temperature, tint and colour saturation of the screen.
The Lumia 630's contrast levels were also higher, measuring 894:1 whereas the Lumia 635 measured 807:1. This didn't make too much of a difference in practice, as the Lumia 635's extra brightness helped illuminate deeper areas of shadow in our test images to help put both phones on a more equal playing field.
Since the Lumia 635 has a higher default brightness, this also had an adverse effect on the phone's battery life. In our continuous video playback test, it lasted 10 hours and 18 minutes. This is over 90 minutes less than the Lumia 630, which lasted 12 hours and 3 minutes. You should still be able to get a day's use out of the Lumia 635, but it's likely to require charging more frequently in the long term than the Lumia 630.
The same goes for the Lumia 635's camera, which produced photos with identical image quality to the Lumia 630. Read our full Nokia Lumia 630 review for a more in-depth look at the camera's picture quality as well as what you can do with the Nokia Camera app.
The Nokia Lumia 630 (left) is a fraction warmer than the Lumia 635 (right), but both phones show an equal amount of detail
The Nokia Lumia 635 is a great value 4G Windows phone, but its shorter battery life than its 3G counterpart may be a bit of a deal-breaker for those hoping to get all the benefits of the Lumia 630 with faster data speeds. We're big fans of both phones, but if 4G isn't a priority, we'd stick with the Lumia 630.