field sport vs fishing

field sport and fishing both are nouns.

Word	Noun	Adjective	Verb	Adverb
field sport	Yes	No	No	No
fishing	Yes	No	No	No

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

Other hyponyms of field sport include hunt, hunting, sportfishing.

field sport (noun)	fishing (noun)
a sport that is played outdoors	the act of someone who fishes as a diversion
	the occupation of catching fish for a living