Vesper vs evening star

Vesper and evening star both are nouns.

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

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

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

Other synonyms of Vesper include Hesperus.

Vesper (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