blood blister vs bleb

blood blister and bleb both are nouns.

Word	Noun	Adjective	Verb	Adverb
blood blister	Yes	No	No	No
bleb	Yes	No	No	No

As nouns, bleb is a hypernym of blood blister; that is, bleb is a word with a broader meaning than blood blister:

blood blister: blister containing blood or bloody serum usually caused by an injury
bleb: (pathology) an elevation of the skin filled with serous fluid

Other hypernyms of blood blister include blister, bulla.

blood blister (noun)	bleb (noun)
blister containing blood or bloody serum usually caused by an injury	(pathology) an elevation of the skin filled with serous fluid