Rape is an action in which there is no uncertainty as to what happened.
An accusation of racism, in a lot of cases, is based on the supposed victim's perception of an interaction with a supposed perpetrator.
If I was rude to someone of a different race, they may feel it is because of their race that I treated them poorly. In which case...racism. The truth, however, may just be because I am shy, a prick, or I don't like them for a myriad of other reasons.
If I slipped a woman a drug, and slept with her while she was passed out, there is not perception needed...that's rape. If I attack a woman from the bushes...rape, no grey area there.
so that's a yes, there are varying degrees of racism? the real kind where you meant it, and the fake kind where the person was just offended