Unicast: A unicast address identifies a single interface and a packet sent to a unicast address is delivered to the one interface identified by that address.
Anycast: An anycast address is for a set of interfaces typically on different nodes. A packet sent to an anycast address is delivered to only one of the interfaces identified by that address. The nearest interface, according to the routing protocol metric, gets the packet delivered to it.
Multicast: A multicast address identifies a set of interfaces typically on different nodes just like an anycast address. However, a packet sent to a multicast address is delivered to all interfaces identified by that address.