Hyper, mega, giga. Hyper came about with Magnum and since then, every designer comes up with it's own name. Even inversions that are identical are called different things by different designers. It's all about marketing. Raging Bull was call the worlds first hyper twister yet the out and back B&M aren't called hyper they are called mega's. It's about trying to seem original and making people think they are riding something that is different from what they've ridden before.
I think the interest in giant coasters has lessened because bigger is not better. The most reputable wooden coasters in recent years are not record breakers, they are better designed to be both more thrilling and more comfortable. The same is ringing true for the steelies. No park wants to use up a huge chunk of geography for one ride that may be large and fast but not very original or exciting.