While there obviously is such an animal as a backtension release, it is really more a method of triggering a release than a type of release. I only use wrist releases for hunting, while I use everything from Stan CNC "real" backtension releases to wrist releases for 3D. I would always want to use BT to trigger these releases, though occasionaly it isn't possible.

About the only thing that I wouldn't call a BT release, at least pottentialy, is something like the GK Answer, or a release with a chunky trigger, etc...