goo vs sapropel

goo and sapropel both are nouns.

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

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

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

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