half-caste vs mixed-blood

half-caste and mixed-blood both are nouns.

Word	Noun	Adjective	Verb	Adverb
half-caste	Yes	No	No	No
mixed-blood	Yes	No	No	No

As nouns, mixed-blood is a hypernym of half-caste; that is, mixed-blood is a word with a broader meaning than half-caste:

half-caste: an offensive term for the offspring of parents of different racial groups or cultures
mixed-blood: a person whose ancestors belonged to two or more racial groups

half-caste (noun)	mixed-blood (noun)
an offensive term for the offspring of parents of different racial groups or cultures	a person whose ancestors belonged to two or more racial groups