theorist vs theoretician

theorist and theoretician both are nouns.

Word	Noun	Adjective	Verb	Adverb
theorist	Yes	No	No	No
theoretician	Yes	No	No	No

As nouns, theorist and theoretician are synonyms defined as:

theorist and theoretician: someone who theorizes (especially in science or art)

Other synonyms of theorist include idealogue, theoriser, theorizer.

theorist (noun)	theoretician (noun)
someone who theorizes (especially in science or art)	someone who theorizes (especially in science or art)