Microwaving sweet vs. white potatoes: why the discrepancy?

Factual Questions
1

I’ve always noticed that a sweet potato takes longer to cook than a similarly-sized white potato. What accounts for the difference?

I know that despite the naming that they’re members of different plant families and are thus not closely related, but the question is not about cladistics, but what structural differences account for the time differences.

I had posted this question once before several years ago, but a search failed to bring it up.

2

Sweet potatoes are harder and have less moisture. Try slicing one up sometime–it’s much more difficult than slicing a white potato.