What is a phychotherapist?

hello!
i'm finally goiung to get some help for my 'suspected bpd'. My question is... what is the difference between a psychotherapist, therapist and a psychologist? can all of them diagnose you? or can only one of them do it? is one just more like a counsellor?
- thanks!

Hope this information helps you:

A psychotherapist interacts with patients to initiate change in the patient’s thoughts, feelings, and behavior through adaptation. Psychotherapists provide treatment in individual and group settings. A licensed psychotherapist obtains a master’s degree or doctorate in a chosen mental health field, undergoes a supervised clinical residency, and is licensed, certified, or registered by a government or psychological agency to which they are accountable. Licensed professionals who practice psychotherapy include the following:

Psychiatrists
Registered psychiatric nurses
Clinical social workers
Marriage therapists
Family therapists
Clinical psychologists

Types of Psychotherapy
Psychotherapists use the following techniques to treat various psychological conditions and situations:

Behavioral therapy (e.g., cognitive behavioral therapy, motivational enhancement therapy, controlled exposure with response prevention)
Biofeedback
Interactive group therapy (e.g., family therapy)
Meditation
Relaxation training
Self-help groups
Psychodynamic therapy

thats great, thanks!