blister vs bulla

blister and bulla both are nouns.

Word	Noun	Adjective	Verb	Adverb
blister	Yes	No	Yes	No
bulla	Yes	No	No	No

As nouns, blister and bulla are synonyms defined as:

blister and bulla: (pathology) an elevation of the skin filled with serous fluid

Other synonyms of blister include bleb.

blister (noun)	bulla (noun)
(pathology) an elevation of the skin filled with serous fluid	the round leaden seal affixed to a papal bull
(botany) a swelling on a plant similar to that on the skin	(pathology) an elevation of the skin filled with serous fluid
a flaw on a surface resulting when an applied substance does not adhere (as an air bubble in a coat of paint)