Yeah, that was the first question on my mind too: "WTF is GHC?". A quick Google search reveals that it's the Glasgow Haskell Compiler. Maybe it makes sense to expand that in the title?
Haskell is a language standard, and GHC is an implementation of that standard. It may be the only one (not sure the status of Hugs, another implementation), but that's the difference, I believe.
Thanks, same here, it rings a bell but I was unsure.