问题
Do Windows Phone 7.1 - 7.8 apps run reasonably well on Windows Phone 8 devices? Is there any reason in terms of compatibility for me to choose one over the other?
回答1:
You will find the official documentation about WP 7.1 and WP 8 platform compatibility in the following link:
App platform compatibility for Windows Phone
Although in general any WP7 app will run without problem in a WP 8 device, this documentation addresses some cases where the behavior may be different.
So, if you don't use any specific features introduced in WP 8, you can develop targetting WP 7.1. That way your app will be available for more people. If you want to take advantage of WP 8 specific features such as NFC or Nokia maps, I would recommend to develop for both platforms, reusing as much code as you can.
回答2:
You can run Windows phone 7 apps on a device with Windows phone 8, but not vice versa. I'd advocate targeting 7.x, unless you need to use 8.x specific hardware like NFC, in which case, I'd advocate targeting specific versions.
来源：https://stackoverflow.com/questions/18066798/compatibility-between-windows-phone-7-1-7-8-apps-and-windows-phone-8-devices