gull vs mug

gull and mug both are nouns.

Word	Noun	Adjective	Verb	Adverb
gull	Yes	No	Yes	No
mug	Yes	No	Yes	No

As nouns, gull and mug are synonyms defined as:

Other synonyms of gull include chump, fall guy, fool, mark, patsy, soft touch, sucker.

gull (noun)	mug (noun)
mostly white aquatic bird having long pointed wings and short legs	with handle and usually cylindrical
a person who is gullible and easy to take advantage of	the human face (`kisser' and `smiler' and `mug' are informal terms for `face' and `phiz' is British)
	a person who is gullible and easy to take advantage of
	the quantity that can be held in a mug

gull (verb)	mug (verb)
fool or hoax	To stare awkwardly
make a fool or dupe of	rob at gunpoint or with the threat of violence