There is a difference in expressing your opinion, however, objectionable, and bullying. I honestly think that some of these laws are created, in principle, to protect religious kids' right to say "I think homosexuality is a mortal sin." I think we all know how, um . . .overenthusiastic, schools can be in enforcing their concept of the rules. If its like the last one I read, its purpose its to protect the right to free speech, and it doesn't permit actual bullying.
That said, I also have no doubt it will used as open season on gay kids, and that some of its supporters know that and are all for it.
The problem with defining bullying, and the reason I'm leery of all bullying laws, is that things that hurt your feelings and make you unhappy aren't necessarily bullying. I was bullied plenty as a kid, so I know what I'm talking about here. These rules should not be used to attempt to protect children from all the ups and downs and hurts and dramas of childhood . . . those are part of growing up. They should not be used to protect children from contrary opinions, or to smother unpopular opinions (having actually gotten in trouble (or gotten bad grades) for having opinions that were in fact, guilty of being too "conservative," I again know of what I speak, although those opinions were not directed at any human beings that would be offended by them except for political reasons)
Defining the exact boundaries for legal purposes is hard . . . and that's why laws against bullying are a bad idea. Assault, harassment, making threats, those are already illegal. All schools should, obviously, have a policy against lower level assault, harassment and cruelty as well . . .and in fact probably do, whether or not they are enforced. But mandating such rules, and then mandating exceptions, by law, is a recipe for mindless, counterproductive enforcement, and equally mindless lack of enforcement. The law (especially when implemented by dim-witted school boards) is an awfully blunt instrument to apply to the cruelties and betrayals of childhood and adolescence . . . as we all should have learned from the current policies schools have that are supposed to make them "safe."
Edit: I am emphatically not defending the right of people to bully for religious reasons . . . but I also recognize that, however rude it might be, people have right to say "I believe homosexuality is wrong," and that right should not end at the schoolhouse door, even if it offends and upsets their classmates or their teacher. Its also not bullying . . . not by itself. But that's the problem isn't it? Finding the difference in a particular situation that makes free speech bullying . . . and that's why laws (let alone arbitrary exceptions) are a bad idea.