Easy way to see is to go to System Settings > About phone > Status > "Mobile network type".
See, Samsung's TouchWiz uses the AT&T nomenclature which is 3G, 4G, 4G LTE, versus the AOSP (also CM, AOKP, PA, etc.) nomenclature which is 3G / H, H+, 4G (respectively). This is due to the rest of the world using standard nomenclature versus the US carriers who try to use marketing gimmicks to sound faster.
Summary:
AT&T | AOSP
3G = 3G / H
4G = H+
4G LTE = 4G