The thing is: Street Fighter 2: TWW, CE, Turbo , Ghouls N Ghosts and most of the other games are ports of the Playstation versions of the Capcom Generation series, which means most of these games are NOT arcade-perfect, although very very close. The ending music in Ghouls N Ghosts is different. there are a few frames of animation missing when Arther powers himself up with the golden armor. In SF2 TWW, the arcade glitch tricks are all gone. there is no proper arcade-operators test/ configuration menu as there is with say, arcade Tekken 1,2,3 that is included with PS2 Tekken 5.
the games that were not part of the Capcom Generation series such as Final Fight and Forgotten Worlds, seem to be of better quality, no major complaints, although you still don't have the original arcade ROM, but a port.
playing all of these games on MAME, or other CPS emulators, gives you a truer arcade experience. but the Capcom Classics Collection games offers you a close-enough experience to the arcade without any real major downgrades such as those you would experience playing on a 16-bit era system like PC-Engine, Genesis, SuperGrafx, SNES, PC, Amiga, etc.