What parts in the Gen II are shared with the Corolla?

Maybe some switches and interior trim but that'll be able it. Even the engine in the Prius is specific to the Prius. It might be a 1.5 but that's about as near as it gets to any other 1.5 Toyota engines.

Without going into full details, the engine in the Prius (gen2 and gen3 and maybe the gen1) works in a completely different way to any other petrol engine in a production car today. It lacks power, hence a 1.8 only gives 100bgp, but gives great fuel economy. The electric motor takes up the slack, almost like a turbo, in a very vague sense of the word.

 

Not entirely true, Grumpy.

There are several interchangeable engine parts for the Toyota/Scion 1.5L engine family from 2001 to 2009. In fact, the 1NZ-FE engine used in the xA, xB, and Yaris is a variant of the Prius 1NZ-FXE engine.

Toyota NZ engine - Wikipedia, the free encyclopedia

So, the Gen II Prius gasoline engine isn't quite as "specific" as you believe it to be.

 

(I know, I was just trying to keep it simple )

I was trying to draw attention that one can't simple remove a Prius engine and replace it with a Yaris one, or vice versa.

All manufacturers use multiple parts from their 'parts bins' and I'm sure the Prius is no exception, but you can't just lug a non Prius engine in as a quick or cheap fix.

 

what about the wheels?

 

Probably the engine, which is why they last so long...