ATF is basically paraffinic, mineral oil. Dexron/Mercon are listed as heavy, hydrotreated, paraffinic distillate. It also has some naphthenic oil as well. To get much more descriptive than that you have to start discussing distilation ranges and such. Of course they also mix in their proprietary blend of rust preventatives, anti-foulants, etc.

Brake fluids can be glycol based, mineral oil or silicone.

Eric