guck vs sapropel

guck and sapropel both are nouns.

Word	Noun	Adjective	Verb	Adverb
guck	Yes	No	No	No
sapropel	Yes	No	No	No

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

guck: any thick, viscous matter
sapropel: sludge (rich in organic matter) that accumulates at the bottom of lakes or oceans

guck (noun)	sapropel (noun)
any thick, viscous matter	sludge (rich in organic matter) that accumulates at the bottom of lakes or oceans