What do hedgehogs and rhinos have in common?

Hedgehogs and Porcupines literally have little to nothing in common.

They are not related, and the only thing that associates the two are quills.

However, there is a large difference between the two even so. A porcupines' quills are extremely sharp, and barbed - that makes them difficult to get out of the victims skin (as the barbs easily detach once stuck into something else, i.e. a victims skin). But a hedgehogs' quills are MUCH duller, and are NOT barbed - and are not dangerous.