If you call someone in, you circle back to a hurtful or oppressive comment they made in private. If you call someone out, you let them know their comment was hurtful in a public space. I’m going to be honest with you, I don’t think one is better than the other. I personally call people out more than I call them in. It’s what I’m more comfortable doing, but that doesn’t mean it is what will work best for you.