They give wisdom, prudence, make a judgment, estimation or make a recommendation when asked. You go to them with a set of issues, and they help you resolve a dilemma. They give advice on what the best course of action seems to be. They are decision centered. They help you make a decision on the best course of action.
Doctors are a good example of an advisor.
Pastors sometimes play advisory roles, but usually when they are an 'expert' in a field. Those more senior, or more experienced are often looked to for advice. A facilitator assists in moving people forward from their present position to a new place. They start somewhere and finish somewhere. They assist, they enable, shining a torch on the dim path.