I think a personal trainer is someone you go to because you want to get fit or you want to get into shape. They can assist you in your fitness journey. Their knowledge is good enough to help you but probably not enough to really take you from A to B. I think their knowledge is fairly limited which is more often than not due to lack of experience.
I think a coach is someone who specialises in their craft. Where you will often see personal trainers claim to specialise is a wide range of things from fat loss to marathon running, a coach will generally have very limited things they specialise in and as result they are very good at what they do. I guess you could compare it to a GP and a Consultant.
When I work with clients I generally work with people who want to transform their physique or people who want to improve their strength. Outside of these parameters I know I would not be the best person for the job. I am able to coach clients who have never performed free weight exercises into competent lifters. I am able to use adequate steps for the individual to get from A to B. I am able to coach clients with their nutrition to get them eating as they should to hit the goals they want to achieve.
My knowledge was very limited before because I didn’t spend time perfecting my craft. I didn’t have the experience of working with a wide variety of clients over many years understanding what works and what doesn't for specific people. I hadn’t been coached myself by someone else helping me to gain knowledge and also improve myself as a trainer and also as a lifter.
I am in no way belittling personal trainers. There is nothing wrong with the job it’s rewarding and empowering. My current job title is as a personal trainer so I’m certainly not going to belittle what I do. I just think it’s a stepping stone to becoming a coach - if that’s what you want to do. My job title may be personal trainer but I believe I’m on the way to becoming a coach. I would like to think those who work with me or have over the last 2-3 years would agree.