garden party vs lawn party

garden party and lawn party both are nouns.

Word	Noun	Adjective	Verb	Adverb
garden party	Yes	No	No	No
lawn party	Yes	No	No	No

As nouns, garden party and lawn party are synonyms defined as:

garden party and lawn party: a party of people assembled for social interaction out of doors

Other synonyms of garden party include fete champetre.

garden party (noun)	lawn party (noun)
a party of people assembled for social interaction out of doors	a party of people assembled for social interaction out of doors