An interconnect is something that joins together two audio-visual devices. For example, the wire joining a TV to an A/V receiver, or the wire that joins a DVD player to a TV. A HDMI cable is an interconnect.
The terms wire or Projector cable generally refer to something that sends audio signals from the amplifier to the speakers. However, these terms are usually used quite interchangeably, and wire/cable are the most common, but it does help to know the difference.