field trip vs outing

field trip and outing both are nouns.

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

As nouns, outing is a hypernym of field trip; that is, outing is a word with a broader meaning than field trip:

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

Other hypernyms of field trip include excursion, expedition, jaunt, junket, pleasure trip, sashay.

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