bibliotheca vs library

bibliotheca and library both are nouns.

Word	Noun	Adjective	Verb	Adverb
bibliotheca	Yes	No	No	No
library	Yes	No	No	No

As nouns, library is a hypernym of bibliotheca; that is, library is a word with a broader meaning than bibliotheca:

bibliotheca: a collection of books
library: a collection of literary documents or records kept for reference or borrowing

bibliotheca (noun)	library (noun)
a collection of books	a depository built to contain books and other materials for reading and study
	a room where books are kept
	a building that houses a collection of books and other materials
	a collection of literary documents or records kept for reference or borrowing
	(computing) a collection of standard programs and subroutines that are stored and available for immediate use