Alpine fir vs subalpine fir

Alpine fir and subalpine fir both are nouns.

Word	Noun	Adjective	Verb	Adverb
Alpine fir	Yes	No	No	No
subalpine fir	Yes	No	No	No

As nouns, Alpine fir and subalpine fir are synonyms defined as:

Alpine fir and subalpine fir: medium-tall timber tree of the Rocky Mountains having a narrowly conic to columnar crown

Other synonyms of Alpine fir include Abies lasiocarpa.

Alpine fir (noun)	subalpine fir (noun)
medium-tall timber tree of the Rocky Mountains having a narrowly conic to columnar crown	medium-tall timber tree of the Rocky Mountains having a narrowly conic to columnar crown