Gypsum board = drywall, so I'm not sure what your question is.
Also, I split this post off to a new thread, since it's really not a continuation of the thread on which it was originally posted.
--Keith :mrgreen:
Let's further define terms...
Gypsum wallboard is the product.
The primary ingredient in the product is gypsum.
It is often generically referred to as drywall. It appears our international friends often call it plasterboard or gyp rock.
A popular brand name of the product is Sheetrock™.
Hopefully that clears things up. :-)
--Keith :mrgreen: