sib vs half blood

sib and half blood both are nouns.

Word	Noun	Adjective	Verb	Adverb
sib	Yes	No	No	No
half blood	Yes	No	No	No

As nouns, half blood is a hyponym of sib; that is, half blood is a word with a more specific, narrower meaning than sib:

Other hyponyms of sib include quad, quadruplet, quin, quint, quintuplet, triplet, twin.

sib (noun)	half blood (noun)
one related by blood or origin; especially on sharing an ancestor with another	one of siblings who have only one parent in common
a person's brother or sister