spray foam insulation vs regular insulation....thanks

You may have to define regular insulation so we know what you are asking.

I was under the impression that regular insulation breathes a lot more than spray foam insulation ie letting heat out and such much more easily. Where spray foam practically seals your house...if that helps

...and what I'm asking is that the main difference?

If you ignore costs, fiberglass(if that is what regular insulation is) can provide a vapor barrier if installed with the kraft paper. Fiberglass will require more space and installation effort.

Foam is basically permanent. I don't know how you deal with wiring or plumbing. It is best for catherdral ceilings where you only have 4 inches to work with.

check out www.energystar.org and look for EERE info on insulation technology.

You might want to read more about foam insulation and learn about the various types used in a home. Spray foam use is all based upon the type of application you require.