party vs garden party

party and garden party both are nouns.

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

As nouns, garden party is a hyponym of party; that is, garden party is a word with a more specific, narrower meaning than party:

party: a gathering of people for pleasure
garden party: a party of people assembled for social interaction out of doors

party (noun)	garden party (noun)
an occasion on which people can assemble for social interaction and entertainment	a party of people assembled for social interaction out of doors
a gathering of people for pleasure
an organization to gain political power
a band of people associated temporarily in some activity
a person involved in legal proceedings

party (verb)	garden party (verb)
have or participate in a party