They both have CDMA and GSM as they are they same model and have the same hardware. When you are using a GSM provider like AT&T then you are using the GSM radio that is part of the hardware of the phone, and when you are using a CDMA provider like Verizon then you are using the CDMA radio that is also part of the hardware of the phone (in addition to LTE and different bands of it that are supported for different carriers).Im aware theyre the same model number but one has CDMA and the other GSM after, unless they do that do confuse us which you can see I am, lol. I went to the Verizon site and it said it was but maybe just LTE?
If you are simply talking about coverage, then that's a carrier-specific thing that isn't really related to the phone. You'd need to check the carrier coverage maps and perhaps get feedback from others in the area about how the coverage is for a particular carrier.