Hi @Former-Member,
Pretty much anyone can call themselves a "psychotherapist" - this is an unregulated term.
A psychologist is someone who has done a 4 year degree plus a 2-year internship.
A clinical psychologist is someone who has done a 4 year degree plus an additional 2-year masters degree.
So...for example, I have a psychology degree, but to become a psychologist I would need to do the 2-year internship (or a masters program).
I hope that helps. Realistically, in my experience, the qualification that someone has is irrelevant to how much they may or may not be able to help you. The best counsellor I have ever had was my uni counsellor and she was a social worker. I think the training that social workers receive prepares them much better for actually helping people than the training that psychologists receive. For example, social workers do a lot of placements (i.e. gaining practical experience out in the real world) during their degree whereas a psychology student does not do any placements or learn any sort of actual counselling skills during the 4-year degree. To me that is absurd!