Yes, the comics are very different, they are even more violent and sexual graphically, and the characters personalitites are different too. Akemi is a horney-ball, Amano Jyaku (I adapted this name to my lanaguage, Catalan, where "y" and "k" don't exist) is much more a bad guy, Megumi is another bitch, etc... The problem is that the part of the movie that impressed me the most was the ending, and the comics I read don't reach that, so I'm very pissed

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Usually, when a comic or a book is very long in pages the movie has to be different by force, as it is just a condensed summary of it. Akira anybody?
Here in Spain very few anime movies are displayed in theatres, only the big ones like Akira, the Miyazaki's (Porco Rosso, Monoke, Spirited Away) and the ones for children (Doraemon, Shin Chan, etc.). The others go directly on VHS/DVD. Hopefully you can also watch quite a lot in TV, specially series.
About Faust, I saw the movie based in that comic, as it was filmed in my city, Barcelona, and it was terrible... angry I'm sure the comics are much better.