Yet both wear clothing which unless you are an evolutionist implies that both are post-fall beings. The crabs don't MAKE anything with these 'skins'. They use them as they find them. The neanderthal had to tan the hide. If not, then they are more knowledgeable in that area.
Tanning is quite a process with lots of sequential steps.
Usually only modern humans today are capbable of such complex activities involving the use of tools. If the Neanderthal had not tanned the hides, he would have had a flock of buzzards following him.