Network Slice Simultaneous Registration Group (NSSRG)

a Network Slice instance can be associated with one or more S-NSSAIs, and an S-NSSAI can be associated with one or more Network Slice instances

eight S-NSSAIs

such S-NSSAI is comprised of either both an SST and an SD or only an SST without a standardised SST value and no SD

Network Slice Simultaneous Registration Group (NSSRG)

Network Slice Admission Control (NSAC)

Network Slice-Specific Authentication and Authorization (NSSAA)

Number of simultaneous connection of Network Slice instances per UE is limited

The AMF instance serving the UE logically belongs to each of the Network Slice instances serving the UE,

Basically APN is controlling network parameters (or configurations) by switching the traffic to various different gateway on the core network.