black hemlock vs Tsuga mertensiana

black hemlock and Tsuga mertensiana both are nouns.

Word	Noun	Adjective	Verb	Adverb
black hemlock	Yes	No	No	No
Tsuga mertensiana	Yes	No	No	No

As nouns, black hemlock and Tsuga mertensiana are synonyms defined as:

black hemlock and Tsuga mertensiana: large evergreen of western United States; wood much harder than Canadian hemlock

Other synonyms of black hemlock include mountain hemlock.

black hemlock (noun)	Tsuga mertensiana (noun)
large evergreen of western United States; wood much harder than Canadian hemlock	large evergreen of western United States; wood much harder than Canadian hemlock