Description

A specialist is a person with great knowledge or skill in a particular field.
And can as well be a person who concentrates primarily on a particular subject or activity; a person highly skilled in a specific and restricted field

A Doctor is a person who is licensed to practice medicine and has trained at a school of medicine or a school ofosteopathic medicine; a physician.
and can as well be Any of certain other healthcare professionals, such as a dentist, optometrist, chiropractor, podiatrist, orveterinarian.