fir vs douglas fir

fir and douglas fir both are nouns.

Word	Noun	Adjective	Verb	Adverb
fir	Yes	No	No	No
douglas fir	Yes	No	No	No

As nouns, douglas fir is a hyponym of fir; that is, douglas fir is a word with a more specific, narrower meaning than fir:

fir (noun)	douglas fir (noun)
any of various evergreen trees of the genus Abies; chiefly of upland areas	tall evergreen timber tree of western North America having resinous wood and short needles
nonresinous wood of a fir tree	strong durable timber of a douglas fir