Coach:
A coach is someone who helps you learn how to do what you want to do yourself with the focus on applying specific skills to your specific situation; increasing your skill set, capabilities, understanding, and confidence. A coach is a teacher and mentor.
Think of actors. An acting coach helps them learn how to act. Once that knowledge is acquired the actor can continue to act over and over again.
An Audiologist coaches people how to understand their hearing and how to use their hearing aid or other devices. The person then uses their newfound knowledge and devices over and over again on their own.
A football coach helps players learn how to play the game. The players go on the field to play, and then take their improved capability to the next team.
Or
Consultant:
A consultant is someone who you hire to do something you don't want to do yourself. A consultant creates a finished product for you, not with you. If you need to do it again you hire the consultant again.
In the consultant model the actor would hire the consultant to play the part. The next time the part was needed the actor still wouldn't be able to do it, but would hire another consultant to play the part.
In the consultant model the Audiologist would work the device all the time and the user would never know how to do it themselves.
In the consultant model the football coach would go out on the field and actually try to play. This would be really funny in the NFL, or even in high school!
Different:
There are times when you want a coach, and times you want a consultant.
It is always good to know when to use each.
You want a coach when you want to do something yourself and want to utilize someone else's experience and knowledge. You want to be the best you can be quickly without making excessive mistakes. Coaches are also best when you have a lot of personal interest in the outcome. How do you want your life to work out? How do you want your business to be? Someone cannot just do your life for you, you want to do it for yourself.
You want a consultant when you want to have someone else do something you don't want to or cannot do yourself. Most of us have a consultant for our taxes. A CPA, they do them, and we get them back completed! Tasks that are best for consultants are items that are somewhat separate from our day to day activities, not a central part of our activity, and can be separated. Or are items that require a specific technical skill we don't have time to learn, an interest in learning, or time to actually do.