In the U.S. a psychologist can be a therapist but they may also do clinical work, research, or testing; the terms aren't distinct from each other. And therapists can be a variety of terms: social workers, licensed professional counselors, psychologists, psychiatrists, psychoanalysts. I may be wrong, but there isn't a single college degree that has the designation psychotherapist; it's a group of professionals of varying educational and certification and licensing backgrounds that can all call themselves psychotherapists. Is it different in your country?