outing vs field trip

outing and field trip both are nouns.

Word	Noun	Adjective	Verb	Adverb
outing	Yes	No	No	No
field trip	Yes	No	No	No

As nouns, field trip is a hyponym of outing; that is, field trip is a word with a more specific, narrower meaning than outing:

outing: a journey taken for pleasure
field trip: a group excursion (to a museum or the woods or some historic place) for firsthand examination

Other hyponyms of outing include airing.

outing (noun)	field trip (noun)
a journey taken for pleasure	a group excursion (to a museum or the woods or some historic place) for firsthand examination
a day devoted to an outdoor social gathering