APN stands for Access Point Name and are the settings your 4GXtream needs to pass to the network carrier; AT&T, Vodafone, T-Mobile, etc. in order for the carrier to allocate your 4GXtream an IP address and connect you to the right secure network.
With the 4GConnect, you have to manually enter the APN settings of your SIM card. However, with the 4G Xtream, it has a “Auto-APN” feature that reads the SIM details and selects the correct APN settings for the SIM’s mobile network.