gritstone vs sandstone

gritstone and sandstone both are nouns.

Word	Noun	Adjective	Verb	Adverb
gritstone	Yes	No	No	No
sandstone	Yes	No	No	No

As nouns, sandstone is a hypernym of gritstone; that is, sandstone is a word with a broader meaning than gritstone:

gritstone: a hard coarse-grained siliceous sandstone
sandstone: a sedimentary rock consisting of sand consolidated with some cement (clay or quartz etc.)

gritstone (noun)	sandstone (noun)
a hard coarse-grained siliceous sandstone	a sedimentary rock consisting of sand consolidated with some cement (clay or quartz etc.)