All these references to Madonna are beyond bizarre.
She's an old hag who has never had a good singing voice and can't act her way out of a paper bag, even when her semi-talented current husband is directing her (and it was even more obvious when she was married to Sean Penn).
Her songs are crap. Christina's songs are the new generation of pop crap. So there's your similarities: blonde hair dye and crap pop songs.
The only difference is: Christina Aquilera can actually SING.
She's calculated, annoying, and boring to listen to in an interview?: Oh, wait, they ARE more similar than I realized at first!!! Madonna's self-importance verges on parody... it's like watching someone whose never been told the truth about themselves flail away with monosyllabic cliches... sort of an Oprah-mixed-with-Babs-Streisand kind of grossness that obliterates everything in its path.
Madonna's "spin" on stealing other people's personas is cool, but the fact that Christina Aquilera has decided to do it too makes her a phony? Pot, kettle calling...
To get down to brass tacks: both apparently know how to market themselves quite well and know who they need in their
PR camps to get them promoted and sell lousy music. Both have no artistic merit to speak of (except that Christina Aquilera can actually sing). Both have shown way too much cooch and titties to ever be considered "female role models" for anyone other than dumb fifteen year olds.