My brother had seen a mt lion in Delevan NY - I have posted to story many times on here so I will not go into details but the one thing he said about the mt lion that really amazed him besides it actually being there in the first place was the muscles in the front shoulders of the animal. He said that everytime it took a step you could distinctly see the muscles and the power it had in its legs. I would think that besides the overall size different between a bob cat and a mt lion this would be one of the determining features that an individual who truely saw a mt lion would notice. ( Not excluding the presence of an "actual" tail )