Why mpls vpn is used instead of mpls?

MPLS VPN is a flexible method to transport and route several types of network traffic using an MPLS backbone between different sites / clients. There are three types of MPLS VPN used in industry. 

mpls vpn is only an application of mpls. types of mpls vpn are mpls l3 vpn, ldp mpls l2 vpn, bgp based mpls l2 vpn, ldp based vpls, bgp based vpls, etc.