printer vs dot printer

printer and dot printer both are nouns.

Word	Noun	Adjective	Verb	Adverb
printer	Yes	No	No	No
dot printer	Yes	No	No	No

As nouns, dot printer is a hyponym of printer; that is, dot printer is a word with a more specific, narrower meaning than printer:

printer: (computer science) an output device that prints the results of data processing
dot printer: a printer that represents each character as a pattern of dots from a dot matrix

Other hyponyms of printer include dot matrix printer, matrix printer.

printer (noun)	dot printer (noun)
a machine that prints	a printer that represents each character as a pattern of dots from a dot matrix
(computer science) an output device that prints the results of data processing
someone whose occupation is printing