As the sightings seem to describe two groups of different animals then I'm regarding them as separate species.
Yahoo - The Aboriginal "Devil-Man"
The Yahoo tends to be quadrupedral and less "monster-like" than the Yowie. It's around 5 ft tall and on rare occasions it stands upright. It has dark fur on its back and it has a lighter underside and head.
Yowie - The Urban Legend
Unlike the Yahoo it walks around on two legs. Its name has now pretty much replaced the older term "yahoo," used in folklore.
|Faked Yowie Sighting|