They are completely different cars. The Celica is a lighter, smaller, 4-cylinder-powered front-wheel drive platform. The all-trac adds full-time all-wheel-drive to the drive train (they are great rally cars).
The Celica Supra (usually just called a Supra these days) is a larger, heavier, rear-wheel-drive platform powered by an inline 6-cylinder engine in recent years or a 4-cylinder in early years.
Celica all-trac:
http://static.cargurus.com/images/si...pic-47705.jpeg
Supra MK3:
http://28.media.tumblr.com/tumblr_l5...ril6o1_500.jpg