barker vs plugger

barker and plugger both are nouns.

Word	Noun	Adjective	Verb	Adverb
barker	Yes	No	No	No
plugger	Yes	No	No	No

As nouns, plugger is a hypernym of barker; that is, plugger is a word with a broader meaning than barker:

barker: someone who stands in front of a show (as at a carnival) and gives a loud colorful sales talk to potential customers
plugger: someone who is an active supporter and advocate

Other hypernyms of barker include booster, promoter.

barker (noun)	plugger (noun)
informal terms for dogs	someone who is an active supporter and advocate
someone who stands in front of a show (as at a carnival) and gives a loud colorful sales talk to potential customers