sticker vs ex libris

sticker and ex libris both are nouns.

Word	Noun	Adjective	Verb	Adverb
sticker	Yes	No	No	No
ex libris	Yes	No	No	No

As nouns, ex libris is a hyponym of sticker; that is, ex libris is a word with a more specific, narrower meaning than sticker:

Other hyponyms of sticker include bookplate.

sticker (noun)	ex libris (noun)
a short knife with a pointed blade used for piercing or stabbing	a label identifying the owner of a book in which it is pasted
an adhesive label
a particularly difficult or baffling question or problem
a small sharp-pointed tip resembling a spike on a stem or leaf