I will admit that I still can't really tell them apart. But the left one in the video is Tuff right?
Heh, it's okay, I still sometimes can't tell them apart. Especially from behind or if they're balled up. MOST especially when they're wrestling. Then it just looks like a big glob of black fur and claws.
But yes, the one on the left is Tuff.
Here's a pretty good profile pic of each of them.
Ruff has wider eyes, and he's noticeable leaner (because he's a bit more active than his brother). The big distinguishing difference is Ruff has a bit of white fur on his chest, and near his private area. I like to think the "Ruff" cane from him kind of looking like he's wearing ruffles.
Honestly, the white fur is how I've often differentiated them, but I'm starting to see who is who without it.
Tuff has an appropriately tougher demeanor. His eyes are kind of naturally droopy or squinted. Heh, I like to think he looks like a cynical detective. He's a LITTLE chonky and lazier than his brother, but not at in unhealthy level (I hope, I need to bring them in for a check up sometime).