milk-vetch vs milk vetch

milk-vetch and milk vetch both are nouns.

Word	Noun	Adjective	Verb	Adverb
milk-vetch	Yes	No	No	No
milk vetch	Yes	No	No	No

As nouns, milk-vetch and milk vetch are synonyms defined as:

milk-vetch and milk vetch: any of various plants of the genus Astragalus

milk-vetch (noun)	milk vetch (noun)
any of various plants of the genus Astragalus	any of various plants of the genus Astragalus