sandstone vs arenaceous rock

sandstone and arenaceous rock both are nouns.

Word	Noun	Adjective	Verb	Adverb
sandstone	Yes	No	No	No
arenaceous rock	Yes	No	No	No

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

sandstone: a sedimentary rock consisting of sand consolidated with some cement (clay or quartz etc.)
arenaceous rock: a sedimentary rock composed of sand

sandstone (noun)	arenaceous rock (noun)
a sedimentary rock consisting of sand consolidated with some cement (clay or quartz etc.)	a sedimentary rock composed of sand