Grizz... I haven't googled this..just working from my admittedly feeble memory...

However, I have always thought that true trout had black spots on a lighter background...That would make browns, cutthroats and rainbows true trout....

Char, on the other hand, have light spots on a dark background, which wouldinclude brookies, lakers , dollies and artic char... I always just thought that bull trout was a name for a large dolly varden..I may be wrong.... Wouldn't be the first time... Just ask my ( EX ) wife........