If it say 4G, without the LTE, then it's HSPA. You can confirm this by going into Settings -> About phone -> Status, then look under "Mobile network type". Now whether its on AWS or 1900MHz, i'm not sure how you can tell.
There service mode on most android phone is by dialing *#*#4636#*#*
This is disabled on the Moto X, but you can get to that menu using the app "Phone testing", which essentially is a shortcut to it. Be careful when you changed the preferred network type, you can't receive calls if you set it as LTE only. The phone don't have capability to make calls with LTE, it revert back 3G/HSPA when there is a call going.