MPLS is a great architecture for transporting various kinds of traffic (hence the name "multi-protocol") from one point to another, through label switched paths (hence the "label switching" part of the name). It is standardized in RFC 3031.
There are two main signaling protocols for MPLS networks to establish label switched paths (LSPs). The Label Distribution Protocol (LDP) and the Resource reSerVation Protocol (RSVP). So what are their differences?
minimal configuration manually configure LSPs on each ingress node
LSPs follow the internal routing you can choose the paths, do traffic engineering.