damson vs damson plum

damson and damson plum both are nouns.

Word	Noun	Adjective	Verb	Adverb
damson	Yes	No	No	No
damson plum	Yes	No	No	No

As nouns, damson and damson plum are synonyms defined as:

damson (noun)	damson plum (noun)
dark purple plum of the damson tree	dark purple plum of the damson tree
	plum tree long cultivated for its edible fruit
	tropical American timber tree with dark hard heavy wood and small plumlike purple fruit