The difference, or subtraction, between120 hertz and 240 hertz is 120 hertz. These two frequencies are typically used to measure the refresh rate of high-definition televisions. Although in theory a higher refresh rate frequency is better, in actuality it makes little difference, explains PC Magazine.
Generally, the frequency of a refresh rate refers to how many frames per second are displayed. One advantage of a high refresh rate is that it reduces the choppiness of fast lateral movement in the source image, found in many kinds of sports broadcasts.
Most source footage has a frame frequency of 24 to 60 hertz. To compensate for the difference between this source frequency and refresh rate on a display, many high-definition television interpolate created frames into the source footage.