A:Answer BT(GPS) requires a Bluetooth connection to an android compatible phone in order to make and receive calls/texts.
LTE does not have that limitation, and you can call from the Watch directly without needing a connection to a phone (assuming you are still in range of a 4G network, of course)
Both still have a microphone and speaker installed.
Unlocked refers to the SIM card installed in the LTE watch. Some 4G Smartwatches come with a SIM card locked to a specific carrier. Apple, for instance, makes a Verizon and AT&T version of their Cellular watches. Samsung makes their Galaxy line Unlocked, meaning you can go to any carrier that accepts smartwatches on their network and have them program the SIM card to work on their network.