To mentor someone is to give them advice, based on your experience in that particular area. A mentor takes someone under their wing and shows them how do to certain things.
A life coach actually allows the client/person to have "self-discovery", which means they use their own abilities to discover what actions to take when pursuing their goals.
So there is a difference between a coach and a mentor. Coaches have specific training where the coaching is about the client, not the coach. In mentoring, you will find you will make references about yourself in helping to advise the person. A coach refrains from referencing themselves, and asks questions of the client so they have the self discovery of answers themselves, instead of the coaching telling them how to achieve something.
Within coaching, there is a journey that you take together with your client.