on-line database vs electronic database

on-line database and electronic database both are nouns.

Word	Noun	Adjective	Verb	Adverb
on-line database	Yes	No	No	No
electronic database	Yes	No	No	No

As nouns, on-line database and electronic database are synonyms defined as:

on-line database and electronic database: (computer science) a database that can be accessed by computers

Other synonyms of on-line database include computer database, electronic information service.

on-line database (noun)	electronic database (noun)
(computer science) a database that can be accessed by computers	(computer science) a database that can be accessed by computers