single-entry bookkeeping vs single entry

single-entry bookkeeping and single entry both are nouns.

Word	Noun	Adjective	Verb	Adverb
single-entry bookkeeping	Yes	No	No	No
single entry	Yes	No	No	No

As nouns, single-entry bookkeeping and single entry are synonyms defined as:

single-entry bookkeeping and single entry: a simple bookkeeping system; transactions are entered in only one account

single-entry bookkeeping (noun)	single entry (noun)
a simple bookkeeping system; transactions are entered in only one account	a simple bookkeeping system; transactions are entered in only one account