[gls2ro]

You made me think more about this subject with this comment. In a way - due to different incentives - I think you are right about the outcome.

As the coach is mostly hired and the mentor internal it might be that the coach has more incentive to push someone to bring their best while the mentor - having as main focus another job and doing mentorship as a side task - will offer advice/guidance but will not have the same incentive to follow through.

Anyhow I agree there is not a standard definition of what a coach or mentor is and what they should do.