black-haired vs dark-haired

black-haired and dark-haired both are adjectives.

Word	Noun	Adjective	Verb	Adverb
black-haired	No	Yes	No	No
dark-haired	No	Yes	No	No

As adjectives, black-haired and dark-haired are synonyms defined as:

Other synonyms of black-haired include brown-haired.

black-haired (adjective)	dark-haired (adjective)
having hair of a dark color	having hair of a dark color
	covered with dark hair