Congrats on your purchase plex! been a longtime since i replied to anything on this forum. Having owned both cars when they were both Stock.
Here are the differences between the 2 cars in its stock state.

The supra and SC were built on the same plant in Japan.
Supra is about a trunk shorter than the SC in length.
Lexus SC fuel tank sits right behind the rear passenger seats, has a full size spare
Sitting in a stock supra for the first time after owning the SC you immediately notice you sit lower, more of a sports car feel.
Turning Radius i think is shorter
The Cabin has a tighter feel especially with the controls curved towards the driver.