Question: what is the difference between dmvpn phase 2 and 3?
Answer: Phase 2 DMVPN forwarding relies exclusively on IP routing table (RIB). Whatever IP next hop is in the routing table (as computed by the routing protocol) is copied into forwarding table (FIB) and used for packet forwarding. In Phase 3 DMVPN, there's the NHRP redirect cache below the forwarding table.