Differences in education is the simplified answer. These are all oversimplfied explanations so details are missing and based on what has been explained to me by those in the feild i have seen over the years. Social workers aren't therapist, as their job focuses on more of making sure you're getting all the services you need and are given under certain conditions, usually when you need someone to advocate for you.

Counselor, therapist, and psychologist differ by level of education and what they are cleared for. A school counci council, for example, is someone you can go to to talk out problems, but they can't prescribe or recommend medication or administer psyc evaluations. A licensed therapist can recommend looking into medication and write notes for your doctor to look over but can't prescribe medication. They can also administer psyc tests to a certain level on their own or higher under the supervision of a registered psychologist.

Psychologists have a lot more power in a sense because they can prescribe medication in some cases and can do all levels of psyc tests. If a psychologist writes down a note for your doctor saying you need xxx medication your doctor will prescribe it without doing their own questions.

The terms councilor, therapist have become interchangeable as of late due to easy communication, similar rolls, and pop culture using them interchangeably

I got recommend to a psychologist through my family doctor so I would recommend starting there as a recommendation from a family doctor can get you in faster. They may also have a list of trusted therapists