MPLS is called multiprotocol because it works with the Internet IP, ATM, and frame relay network protocols. With reference to the OSI model, MPLS allows most packets to be forwarded at the layer 2 (switching) level rather than at the layer 3 (routing) level. In addition to moving traffic faster overall, MPLS makes it easy to manage a network for quality of service (QoS).
A Label Switch Path (LSP) can be established in MPLS that crosses multiple Layer 2 transports like ATM, Frame Relay or Ethernet. Thus, one of the true promises of MPLS is the ability to create end-to-end circuits, with specific performance characteristics, across any type of transport medium, eliminating the need for overlay networks or Layer 2 only control mechanisms.
IPLC basically Layer 1 Connection, And you can get all Layer 2 features like vlan tag, Trunk, STP etc.