5G SA means real 5G. 5G NSA means 4G over 5G NR.

They created an option to use just the 5G radio modem parts with 4G tower equipment to run them in the "Non-StandAlone" mode, so that telcos can start deploying 5G before even it matures. And the modem parts and their specs are called "5G New Radio", which is one of names of all time.