subalpine larch vs larch tree

subalpine larch and larch tree both are nouns.

Word	Noun	Adjective	Verb	Adverb
subalpine larch	Yes	No	No	No
larch tree	Yes	No	No	No

As nouns, larch tree is a hypernym of subalpine larch; that is, larch tree is a word with a broader meaning than subalpine larch:

subalpine larch: medium-sized larch of the Rocky Mountains; closely related to Larix occidentalis
larch tree: any of numerous conifers of the genus Larix all having deciduous needlelike leaves

Other hypernyms of subalpine larch include larch.

subalpine larch (noun)	larch tree (noun)
medium-sized larch of the Rocky Mountains; closely related to Larix occidentalis	any of numerous conifers of the genus Larix all having deciduous needlelike leaves