sign of the zodiac vs star sign

sign of the zodiac and star sign both are nouns.

Word	Noun	Adjective	Verb	Adverb
sign of the zodiac	Yes	No	No	No
star sign	Yes	No	No	No

As nouns, sign of the zodiac and star sign are synonyms defined as:

sign of the zodiac and star sign: (astrology) one of 12 equal areas into which the zodiac is divided

Other synonyms of sign of the zodiac include house, mansion, planetary house, sign.

sign of the zodiac (noun)	star sign (noun)
(astrology) one of 12 equal areas into which the zodiac is divided	(astrology) one of 12 equal areas into which the zodiac is divided