MIDI Timecode is a form of sync that is sent from one master device to another usually via MIDI cables or serial cables. A MIDI Timecode message contains address information, whereas MIDI Beat Clock does not carry address information. MTC is a continuous message, and is a form of frame-accurate sync.
MTC is often the result of SMPTE conversion from a hardware converter like the MTP AV and Digital Timepiece. As well, most computer based sequencers, and some hardware sequencers (like the Akai MPC 2000) can synchronize and transmit MTC.