special interest group vs advocacy group

special interest group and advocacy group both are nouns.

Word	Noun	Adjective	Verb	Adverb
special interest group	Yes	No	No	No
advocacy group	Yes	No	No	No

As nouns, special interest group and advocacy group are synonyms defined as:

special interest group and advocacy group: an interest group that tries to influence legislators or bureaucrats to act in their favor, typically through lobbying

Other synonyms of special interest group include lobby, lobby group, pressure group, special-interest group, special interest, third house.

special interest group (noun)	advocacy group (noun)
an interest group that tries to influence legislators or bureaucrats to act in their favor, typically through lobbying	an interest group that tries to influence legislators or bureaucrats to act in their favor, typically through lobbying