Agreed. If you listen to Signals, which is about 50/50 Rick and Jazz, the tones are clearly very different.
The confusion between the two seems to stem from Moving Pictures, on which both basses are treated with a fair bit of distortion, so telling them apart is tricker.
Also, on Moving Pictures, Geddy played the Jazz on the neck pickup so it sounds less like the scooped Jazz sound we're used to hearing from him.