Rolodex vs card index

Rolodex and card index both are nouns.

Word	Noun	Adjective	Verb	Adverb
Rolodex	Yes	No	No	No
card index	Yes	No	No	No

As nouns, card index is a hypernym of Rolodex; that is, card index is a word with a broader meaning than Rolodex:

Rolodex: (trademark) a desktop rotary card index with removable cards; usually used for names, addresses, and telephone numbers
card index: an alphabetical listing of items (e.g., books in a library) with a separate card for each item

Other hypernyms of Rolodex include card catalog, card catalogue.

Rolodex (noun)	card index (noun)
(trademark) a desktop rotary card index with removable cards; usually used for names, addresses, and telephone numbers	an alphabetical listing of items (e.g., books in a library) with a separate card for each item