Differences between the two Nexus 5 models, D820 and D821

Just like many smartphones, the Nexus 5 actually has two models.There is one version for North America and another for the rest of the world. Both models look the same, and share many of the same specs. The buttons, colors, cameras are the same. The differences are in connectivity, something that you don't see. The radios in each phone are a little different.

The D820 version of the Nexus 5 is designed for North America and will connect to 2G, 3G or LTE on AT&T, T-Mobile and Sprint. The D821 version of the Nexus 5 is set up to work with the rest of the world. European users should have no problem with a 2G, 3G or LTE connection. But some of the Asian carriers that use different networks could pose a problem. For example, China Mobile uses a proprietary 3G pipeline that has kept the Apple iPhone off the roster of the world's largest carrier.


source: AndroidCentral