Psychiatrist, Psychologist, Therapist - what is the difference?

Many people are confused about what the difference is between these three different types of mental health professionals.
A Psychiatrist is a Medical doctor (M.D)
who works with patients to treat mental illnesses. These medical doctors may prescribe drugs such as antidepressants or antianxiety medications to their patients to treat mental illnesses. As an M.D., the required training involves an appropriate Bachelor’s degree, completion of a four-year medical school, completion of a four-year psychiatric residency, state licensing, and board certification. It does not require them to have any training in doing psychotherapy.
A Psychologist is a person holding a P.hD or a Psy.D degree.
These mental health professionals diagnose and treat patients with mental illnesses, but many Psychologists choose to focus on studying or researching human behavior and thinking throughout society. Psychologists do not prescribe drugs or medications to their patients since they are not medical doctors. As a doctorate-level mental health professional the required training involves an appropriate four-year undergraduate-degree, and a doctorate degree in psychology which may take up to seven additional years of postgraduate study depending on the Psychologist’s field of emphasis.
A Therapist, Psychotherapist, Marriage & Family Therapist, or Licensed Clinical Social-Worker holds a Masters Degree

Works with people having difficulties with things in life such as relationships, stress, grieving, or adjustments to changes in life. Masters level counselors or therapists usually help patients with issues relating to relationship problems or coping with changes in life.

In some cases people will seek the help of a Therapist because they may just want to improve themselves, have better relationships with others, understand themselves better or develop a clearer understanding of their own behavior and why they continue to do what they do.