They're both equally stupid, ignorant, childish, and wrong, but society doesn't yet see them that way. Racism became very unpopular only around the 60's. Blacks have been struggling for equal rights, however, since the 1800s. That's a lot of time for society to get used to the idea of black people having the same rights, and black people being the same as any other race. In contrast, gays have only really been in the spotlight since somewhere in the 70's. A lot more ground has been covered faster than was covered for black people for gays, but they still aren't quite at the level of acceptance that black people are at. Since there are many more homophobes than racists right now, it is seen as much less of a bad thing to be homophobic.