The hardware of the two models is identical.

If you have not yet bought one or have several ZYXEL devices, there is now an additional variant "Zyxel Router NR7101 NebulaFlex Outdoor LTE Modem", which should be available around the end of February 2022.

This new variant is ZYXEL Nebula capable (the cloud-based, centralised management solution from ZYXEL). It is (unfortunately from personal experience) the case that the "old" model cannot be updated to Nebula capability via firmware despite the identical product designation, but needs this new hardware version, which was also confirmed to me by ZYXEL Nebula Support.

No difference as far as I understand. I ordered the one advertised here and 5G is running!