Hesperus vs evening star

Hesperus and evening star both are nouns.

Word	Noun	Adjective	Verb	Adverb
Hesperus	Yes	No	No	No
evening star	Yes	No	No	No

As nouns, Hesperus and evening star are synonyms defined as:

Hesperus and evening star: a planet (usually Venus) seen at sunset in the western sky

Other synonyms of Hesperus include Vesper.

Hesperus (noun)	evening star (noun)
a planet (usually Venus) seen at sunset in the western sky	a planet (usually Venus) seen at sunset in the western sky