small boat vs gig

small boat and gig both are nouns.

Word	Noun	Adjective	Verb	Adverb
small boat	Yes	No	No	No
gig	Yes	No	No	No

As nouns, gig is a hyponym of small boat; that is, gig is a word with a more specific, narrower meaning than small boat:

Other hyponyms of small boat include canoe, cockleshell, coracle, dinghy, dory, rowboat, racing boat, skiff, yawl.

small boat (noun)	gig (noun)
a boat that is small	a booking for musicians
	small two-wheeled horse-drawn carriage; with two seats and no hood
	tender that is a light ship's boat; often for personal use of captain
	long and light rowing boat; especially for racing
	an implement with a shaft and barbed point used for catching fish
	a cluster of hooks (without barbs) that is drawn through a school of fish to hook their bodies; used when fish are not biting