Q. Measure of speed in Page or line Printer?

Measure of speed relies on whether the printer is a Page Printer or Line.

Printer: Let's understand these: 

Line Printer:   Line Printer processes and prints only one line of text at a time. 

Page Printer:   A page printer processes and prints whole one page at a time. 

Essentially it rasterizes full image of the page in its memory and then prints it as one line of dots at a time. For a line printer, the speed is measured in characters per second (cps) while for page printing, it is pages per minute (ppm). Henceforth Dot Matrix generally have speeds given in cps while Lasers have speed in ppm. The actual speed may differ from the rating speed given by manufacturer because as expected the printer chooses the more favourable values.