accounting system vs ledger

accounting system and ledger both are nouns.

Word	Noun	Adjective	Verb	Adverb
accounting system	Yes	No	No	No
ledger	Yes	No	No	No

accounting system (noun)	ledger (noun)
a bookkeeper's chronological list of related debits and credits of a business; forms part of a ledger of accounts	an accounting journal as a physical object
	a record in which commercial accounts are recorded