What's the difference between a PhD level psychotherapist and a psychologist?

Can be same, maybe. All psychologists have PhD is psychology, but not all do therapy, so would have to look for someone with experience in Clinical psychology. There is a degree now called PsyD which is also a doctorate level and they usually do therapy. Other degrees that do therapy are Social workers (MSW or LCSW) or Licensed counselors (LPC), but these are usually Master's level but can be excellent therapists.