black whale vs cachalot

black whale and cachalot both are nouns.

Word	Noun	Adjective	Verb	Adverb
black whale	Yes	No	No	No
cachalot	Yes	No	No	No

As nouns, black whale and cachalot are synonyms defined as:

black whale and cachalot: large whale with a large cavity in the head containing spermaceti and oil; also a source of ambergris

Other synonyms of black whale include Physeter catodon, sperm whale.

black whale (noun)	cachalot (noun)
large whale with a large cavity in the head containing spermaceti and oil; also a source of ambergris	large whale with a large cavity in the head containing spermaceti and oil; also a source of ambergris
small dark-colored whale of the Atlantic coast of the United States; the largest male acts as pilot or leader for the school