There's a crucial distinction between a Christian baker refusing to participate in celebrating a gay marriage and Bruce Springsteen refusing to play in NC.
In refusing to perform, Springsteen didn't refuse his services to or against a particular person or persons because of who they are. That would be discrimination. Essentially because of that, by refusing to perform, his was a protest.
If he had refused to perform or withhold services to members of an audience because some were black or because some were heterosexual or because they were not heterosexual or because some were Christian, and he considered any of those offended his conscience, that would be discrimination.
So he was protesting against the government of a state which was discriminating against people because of who they are.
So after your long rambling discourse the reality is that there is no difference. Except that Bruce Springsteen broke a written business contract and now will be sued.
Artists would be better off keeping their performance dates in NC and using the performance to outline their opposition to HB2. In fact this is what the LGBT community in our state is requesting artists to do.