RV construction types....

Hi All,
My questions here will make it very apparent that I am new
to the RV thing as I have mentioned before. lol. But here
goes..

I am seeing several styles of RV here.

- The (older style?) ones with the ruffley sides. The
ruffles are lengthwise, I guess adding stiffness.
Are these aluminum? It seems to me it would be hard to
seal windows and doors well if you are sealing a flat
thing to a ruffley thing.

- The Smooth sided ones. As I understand these are usually
a laminate of several materials? Vacuum and cured?
Fiberglass and wood?

- Aluminum airstream types. Not sure what is just under
the aluminum.

I am wondering what the plusses and minuses are.

I also guess some manufacturers have proprietary build-ups
that they tout as better?

thanks,
groundhogy