Huge difference between the two, in both care and appearance. BTAs reproduce frequently, Ritteris not so much.
In terms of removing BTAs, I've heard a lot of suggestions -- everything from rubbing an icecube on the foot to facing a powerhead at it to either blow it off or irritate it enough that it tries to move on its own. BTAs typically like to bury their foot deep into a rock crevice so they are hard to remove.
In the past, I've used the hammer and chisel approach. To me, it works the best and I feel it is actually the least stressful on the nem since it can be done quickly. It's exactly as it sounds -- you remove the rock it's on from the tank, then carefully chisel around the nem until you can either remove the portion of rock it's on, or you break away enough rock that you can carefully remove it.
