tufa vs volcanic rock

tufa and volcanic rock both are nouns.

Word	Noun	Adjective	Verb	Adverb
tufa	Yes	No	No	No
volcanic rock	Yes	No	No	No

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

tufa: hard volcanic rock composed of compacted volcanic ash
volcanic rock: extrusive igneous rock solidified near or on the surface of the Earth

tufa (noun)	volcanic rock (noun)
a soft porous rock consisting of calcium carbonate deposited from springs rich in lime	extrusive igneous rock solidified near or on the surface of the Earth
hard volcanic rock composed of compacted volcanic ash