card index vs Rolodex

card index and Rolodex both are nouns.

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

As nouns, Rolodex is a hyponym of card index; that is, Rolodex is a word with a more specific, narrower meaning than card index:

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

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