computer database vs on-line database

computer database and on-line database both are nouns.

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

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

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

Other synonyms of computer database include electronic database, electronic information service.

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