What is the difference between a mentor and a coach? Here is my simple explanation:
A mentor looks after your interests whereas a coach looks after your skills.
A mentor is normally an older person in the same organization who takes a younger colleague under his or her wing. As far as I am concerned, the mentor has two main tasks: to promote a career path for the junior person (by speaking up for this person in meetings and introducing him or her to other powerful people) and by telling the person how to fit in better (style, behavior, dress, projects to volunteer for, and so on). Thus, a mentor will help you get ahead by opening doors for you.
Outside or external mentors don’t really help you get ahead in the same organization, but can still help you with your career in general, by introducing you to other industry players, for example.
A coach helps you to perform better or be more successful, however you define performance and success. For example, as an executive coach, I mainly focus on helping executives become more effective at what they do, or should do, to achieve the outcomes that matter for their organization. Other coaches might focus on achieving different things: help you spot issues as they develop, deal with problem areas, work on your strengths, encourage you to eliminate weaknesses, stuff like that.
Here is my simple summary: A coach will help you get yourself ahead whereas a mentor will help you get ahead.
In other words, you should have both.
Which is why I encourage and help my clients to identify potential mentors at various stages in their career.