blocking agent vs blocker

blocking agent and blocker both are nouns.

Word	Noun	Adjective	Verb	Adverb
blocking agent	Yes	No	No	No
blocker	Yes	No	No	No

As nouns, blocking agent and blocker are synonyms defined as:

blocking agent and blocker: a class of drugs that inhibit (block) some biological process

blocking agent (noun)	blocker (noun)
a class of drugs that inhibit (block) some biological process	a class of drugs that inhibit (block) some biological process
	a football player whose responsibility is to block players attempting to stop an offensive play