cross-reference vs cross-index

cross-reference and cross-index both are nouns.

Word	Noun	Adjective	Verb	Adverb
cross-reference	Yes	No	No	No
cross-index	Yes	No	Yes	No

As nouns, cross-reference and cross-index are synonyms defined as:

cross-reference and cross-index: a reference at one place in a work to information at another place in the same work

cross-reference (noun)	cross-index (noun)
a reference at one place in a work to information at another place in the same work	a reference at one place in a work to information at another place in the same work

cross-reference (verb)	cross-index (verb)
	make an index that refers from one point to the next