benchmark vs touchstone

benchmark and touchstone both are nouns.

Word	Noun	Adjective	Verb	Adverb
benchmark	Yes	No	No	No
touchstone	Yes	No	No	No

As nouns, touchstone is a hypernym of benchmark; that is, touchstone is a word with a broader meaning than benchmark:

benchmark: a standard by which something can be measured or judged
touchstone: a basis for comparison; a reference point against which other things can be evaluated

Other hypernyms of benchmark include criterion, measure, standard.

benchmark (noun)	touchstone (noun)
a standard by which something can be measured or judged	a basis for comparison; a reference point against which other things can be evaluated
a surveyor's mark on a permanent object of predetermined position and elevation used as a reference point