Fun celeb fact: In addition to being young moms, Christina Aguilera and Katie Holmes share the same birthday (Dec. 18). On Sunday the singer turns 31 and the actress/designer will be 33.
PHOTOS: SEE CHRISTINA AND KATIE'S HAIR OVER THE YEARS
And while their styles are dramatically different -- Aguilera is known for her super-sexy, over-the-top looks, Holmestypically goes for chic, high-fashion ensembles -- they've both changed up their hair several times in the last decade.
PHOTOS: Biggest celeb hair makeovers of 2011
Click through to see the stars' hair through the years and tell Us which look you like best on each one!
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