All nations have blood on the hands historically, but that does not make their atrocities equal.
A few examples, both Great Britain and the U.S. practiced slavery, but the plantation system and the institutionalized racism was far more brutal. The U.S. committed genocide against the native Americans, but they didn't gas and burn them as a matter of policy. Towards the end of WW2, if you were German who would you rather have surrendered to, U.S./Britain or Russian forces?