VPN and MPLS are widely used technologies for connecting across HUB and remote sites. IPSec VPN being the 1st entrant of 2, was quite a hit since it leveraged the Internet connectivity while providing security and access to central Data Center applications. The need for improved customer experience and reliability led to invent of MPLS which further benefited by allowing overlapping customer IP subnets to communicate across same Provider infrastructure
Drawback with VPN being overhead (bits used in encryption) and latency which is not substantial in case of MPLS.Infact multicast and Dynamic Routing protocol traffic traversal via IPSec tunnels requires additional overhead of GRE tunnel creation (additional bits used for GRE header). VPN generally works on Internet which is cheaper than MPLS, however using Internet is less stable and traffic flows on best effort basis. Infact using delay sensitive and mission critical media over VPN will not be a wise decision.
Further differences between both VPN and MPLS have been discussed in below table –