is the apple thunderbolt display just a moniter

Your question isn't completely clear. The iMac display is a monitor running off the system I/O bus. A Thunderbolt display is a high speed monitor connected to the Thunderbolt bus.

You don't mean a iMac display but the Apple Thunderbolt Display. Reading the specs it seems to be just a monitor but it will only work with a computer that has a thunderbolt port which at this time that is only newer mac computers.