brownstone vs sandstone

brownstone and sandstone both are nouns.

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

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

brownstone: a reddish brown sandstone; used in buildings
sandstone: a sedimentary rock consisting of sand consolidated with some cement (clay or quartz etc.)

brownstone (noun)	sandstone (noun)
a row house built of brownstone; reddish brown in color	a sedimentary rock consisting of sand consolidated with some cement (clay or quartz etc.)
a reddish brown sandstone; used in buildings