GET VPN (Group Encrypted Transport VPN) is a tunnel-less VPN technology that uses a single security association (SA) for all routers in a group. This allows GET VPN to natively support MPLS and private IP networks, without requiring any additional encapsulation or tunneling protocols. GET VPN also supports multicast traffic without GRE, which reduces overhead and improves performance. FlexVPN is a newer VPN solution that covers all VPN types, such as site-to-site, hub and spoke, and remote access. FlexVPN uses IKEv2 for all VPN types, which offers some advantages over IKEv1, such as resiliency and fewer messages. However, FlexVPN requires newer hardware and software versions to support its features. FlexVPN also relies on GRE or static and dynamic point-to-point interfaces to support MPLS and private IP networks, which adds complexity and overhead. Therefore, a benefit of using GET VPN over FlexVPN within a VPN deployment is that GET VPN natively supports MPLS and private IP networks, without requiring any additional encapsulation or tunneling protocols. References:

Group Encrypted Transport VPN (GETVPN)

Introduction to FlexVPN

what is the difference between dmvpn and flexvpn