First, Guitar Hero: Aerosmith is NOT Guitar Hero 4 it's the middle game between Guitar Hero 3 and Guitar Hero 4 just like Guitar Hero: Encore was to Guitar Hero 2 and Guitar Hero 3.
Also, if it's going to be any number it should be Guitar Hero 5 because the timeline looks like this:
1.) Guitar Hero 1
2.) Guitar Hero 2
3.) Guitar Hero: Encore Rocks the 80's
4.) Guitar Hero 3
(some really smart people leave the company)
5.) Guitar Hero: Aerosmith - Hi, I'm the fifth game...
So why people call it GH4, I don't know. I think it's because Guitar Hero: Aerosmith was completely unexpected and almost seems like it was thought of at the last second. While people have been salivating over and expecting Guitar Hero IV since Guitar Hero III came out. So when they heard of a Aerosmith Guitar Hero they thought Activision had REALLY gone in another direction by making the rest of the Guitar Hero games about one band.
Don't worry, even Activisions not that crazy. Well...
So this June we get Guitar Hero: Aerosmith, hopefully they took that opportunity to try new things in the game for GH4. Then we should see Guitar Hero: On Tour for the DS and Guitar Hero 4 ( with multiple bands ).
It will be really interesting to see what Activision does or doesn't do with Guitar Hero: Aerosmith and Guitar Hero 4, but they are definatly not the same game.
