tightrope walker vs acrobat

tightrope walker and acrobat both are nouns.

Word	Noun	Adjective	Verb	Adverb
tightrope walker	Yes	No	No	No
acrobat	Yes	No	No	No

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

tightrope walker: an acrobat who performs on a tightrope or slack rope
acrobat: an athlete who performs acts requiring skill and agility and coordination

tightrope walker (noun)	acrobat (noun)
an acrobat who performs on a tightrope or slack rope	an athlete who performs acts requiring skill and agility and coordination