contortionist vs acrobat

contortionist and acrobat both are nouns.

Word	Noun	Adjective	Verb	Adverb
contortionist	Yes	No	No	No
acrobat	Yes	No	No	No

As nouns, acrobat is a hypernym of contortionist; that is, acrobat is a word with a broader meaning than contortionist:

contortionist: an acrobat able to twist into unusual positions
acrobat: an athlete who performs acts requiring skill and agility and coordination

contortionist (noun)	acrobat (noun)
an acrobat able to twist into unusual positions	an athlete who performs acts requiring skill and agility and coordination