Well I don't see much differences with the story told in FF VII.
indeed there are some changes. But as Helix said it's normal.
Otherwise, there are plenty of things in CC that are excactly as in FF VII.
Like in one off the emails you recieve from tifa, where she's talking about a blond guy in soldier (the promise Cloud made to her)
And in FF VII when you're talking to Aerith in the park, she says she had a sort of boyfriend (Zack)
And there are more of those.
And off course they need an enemy (since Sephiroth was one of the good guys untill the event in Nibelheim) so they brought in genesis.
my opinion, tell me if i'm wrong
