Circuit Cross Connect (CCC) is a simplistic protocol that can be used to connect logical layer 2 interfaces or MPLS LSPs. It can be used to creating layer 2 switching paths, connecting distant l2 logical circuits and stitching MPLS LSPs that could form part of two different TED databases.
MPLS Interface Tunnelling is used to connectivity logical PE-CE attachment circuits across an MPLS core in the same way as a l2circuit would operate. This requires bidirectional LSPs to transport the traffic. No inner labels are used for this, CCC handles the internal traffic carried within the LSP.