Why can't a thermosetting plastic be stretched like an elastomer?

So far I've learnt that there are 2 'types' of thermosets: thermosetting plastics and thermosetting elastomers. Both of them consists of crosslinks that when stretched, allows for the material to spring back into its original shape. So why can't a thermosetting plastic be stretched like an elastomer? Is it something to do with the degree of crystallinity and elastomers being amorphous?


Sorry if my question is a bit messy, I'm quite new to this topic.


