lake vs lagoon

lake and lagoon both are nouns.

Word	Noun	Adjective	Verb	Adverb
lake	Yes	No	No	No
lagoon	Yes	No	No	No

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

lake: a body of (usually fresh) water surrounded by land
lagoon: a body of water cut off from a larger body by a reef of sand or coral

lake (noun)	lagoon (noun)
a body of (usually fresh) water surrounded by land	a body of water cut off from a larger body by a reef of sand or coral
any of numerous bright translucent organic pigments
a purplish red pigment prepared from lac or cochineal