What are two icmpv6 messages that are not present in icmp for ipv4?

Two ICMPv6 messages not present in ICMP for IPv4 are Neighbor Solicitation and Neighbor Advertisement. These messages are used in the Neighbor Discovery Protocol (NDP) to facilitate address resolution and to determine the link-layer addresses of neighboring nodes. Additionally, ICMPv6 includes the Router Solicitation and Router Advertisement messages, which help in the discovery of routers on the local network, a feature not directly available in IPv4 ICMP.