有些回答都不太对。
most times, almost same, both means "don't". sometimes, it's different. For example, 1. 不要脸,you can't say 别脸 2. 不要命,you can't say 别命 these two examples above both want to express "don't want", not "don't" maybe there are other means, I can't remember all.
https://www.italki.com/question/348520