4G is the established cellular network and remains a very good and often entirely adequate solution for many applications in remote maintenance, monitoring and telemetry.
5G NSA (Non-Stand-Alone) already utilises 5G radio technology, but still relies on existing 4G infrastructure for network deployment.
5G SA (Stand-Alone) is the full 5G variant with a standalone 5G architecture. For you, it is less the abbreviation that matters than the question of what your location actually supports and what requirements your application places on data rate, availability and future-proofing.
With the MRcard MSI.5G, the following theoretical maximum data rates of the radio interface are possible:
5G NSA: up to 3.4 Gbit/s downlink / 0.46 Gbit/s uplink
5G SA: up to 2.5 Gbit/s downlink / 0.90 Gbit/s uplink
4G (LTE Cat 19): up to 1.6 Gbit/s downlink / 211 Mbit/s uplink
In practice, however, the following applies: the actual performance achievable always depends on network availability, the provider, the tariff, the antenna design, the installation situation and the actual coverage at the location. If 4G reliably meets your requirements, there is not automatically a reason to switch to 5G. However, if higher data rates, greater future-proofing or generally higher demands on the cellular connection are required, 5G is the right option.