There are several questionable assumptions there, but start with the idea that people who "merely" think another race inferior are worse than those who have an animus or hostility against a different racial group.
Somebody's feeling that you are inferior may actually be stronger and more pernicious and harder to uproot than your "hatred" of them. I'm not saying that it always is, but it's certainly possible.
I still think race hatred is worse than simple prejudices developed by environment and / or education ( or lack thereof). Hatred leads to closed minds and often to violence.
Closed minds and violence do not allow free discussion and do not lead to the education and the elimination old prejudices.