
Some undead are easier to ID than others. Skeletons? Obvious, mostly. Bare bones, maybe with some rags, though there are some skeleton-like undead that can trip you up. Zombies? Rotting flesh, possibly with bits falling off. Mummies? Wrapped up. Wraiths? Dark, shadowy, and, well, wraith-like.
But ghouls, ghasts, and wights look pretty similar. The "spectral" undead can be hard to distinguish too. I'm not sure there's any way to know a spectre from a ghost until it has attacked.
Short answer: the undead whatevers don't seem to be skeletons or zombies. Other than that, you'd have to get closer to them to find out.
