sapropel vs goo

sapropel and goo both are nouns.

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

As nouns, goo is a hypernym of sapropel; that is, goo is a word with a broader meaning than sapropel:

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

Other hypernyms of sapropel include gook, goop, guck, gunk, muck, ooze, slime, sludge.

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