character-at-a-time printer vs character printer

character-at-a-time printer and character printer both are nouns.

Word	Noun	Adjective	Verb	Adverb
character-at-a-time printer	Yes	No	No	No
character printer	Yes	No	No	No

As nouns, character-at-a-time printer and character printer are synonyms defined as:

character-at-a-time printer and character printer: a printer that prints a single character at a time

Other synonyms of character-at-a-time printer include serial printer.

character-at-a-time printer (noun)	character printer (noun)
a printer that prints a single character at a time	a printer that prints a single character at a time