Differences between git branches using Visual Studio

I'm trying to understand how to compare branches or commits using VS 2015.

Using other Git programs, I can easily compare versions, but I can't see how it's done in VS.

Can anyone help?

I just spent a bit of time playing with the current version of VSTS and figured it out (as of October 2016):

1. Go to Code -> Branches
2. Click on the commit diff count to the right of the updated date as in this screenshot:

This will take you to a page that shows both a commit difference between the two, and a file comparison