BG95-M3 AT+QCSQ command response with NBIoT and eMTC

I have a question about the BG95-M3 modem. I currently work with multiple BG95-M3 modems. When I send the AT+QCSQ command some of the modems respond as NBIoT while others as eMTC. Why are they different and what is the difference? Also, if a modem is an eMTC will it switch back to the NBIoT and under what circumstances?

Refer below thread if it helps;

AT+QCSQ reliability vs timing after power-up (BG95) - IoT Modules / LPWA Module - Quectel Forums