Explanation:

Impact printer refers to a class of printers that work by banging a head or needle against an ink ribbon to make a mark on the paper. This includes dot-matrix printers, daisy-wheel printers, and line printers.
A dot matrix printer is an impact printer that prints using a fixed number of pins or wires. In contrast, inkjet and laser printers technically exhibit dot matrix printing, but they are not considered "dot matrix printers". Impact vs. non-impact is one way in which printers are divided into two classes.