olive drab vs olive-drab uniform

olive drab and olive-drab uniform both are nouns.

Word	Noun	Adjective	Verb	Adverb
olive drab	Yes	No	No	No
olive-drab uniform	Yes	No	No	No

As nouns, olive drab and olive-drab uniform are synonyms defined as:

olive drab and olive-drab uniform: military uniform of the United States Army; made from cloth of a dull olive color

olive drab (noun)	olive-drab uniform (noun)
a cloth of an olive-brown color used for military uniforms	military uniform of the United States Army; made from cloth of a dull olive color
military uniform of the United States Army; made from cloth of a dull olive color
a dull greyish to yellowish or light olive brown