Carbamide Peroxide and Hydrogen Peroxide are both ingredients used to whiten teeth by breaking down stains and discoloration. Carbamide Peroxide works in a more gentle manner because it breaks down and releases Hydrogen Peroxide over time. Hydrogen Peroxide works more quickly because it is already in its active whitening form. In simple terms, Carbamide Peroxide provides a slower, longer-lasting release, while Hydrogen Peroxide delivers faster whitening action.