ditto vs ditto mark

ditto and ditto mark both are nouns.

Word	Noun	Adjective	Verb	Adverb
ditto	Yes	No	Yes	No
ditto mark	Yes	No	No	No

As nouns, ditto and ditto mark are synonyms defined as:

ditto and ditto mark: a mark used to indicate the word above it should be repeated

ditto (noun)	ditto mark (noun)
a mark used to indicate the word above it should be repeated	a mark used to indicate the word above it should be repeated

ditto (verb)	ditto mark (verb)
repeat an action or statement