The main difference between a 60Hz and a 144Hz monitor is the refresh rate. A 60Hz monitor has a refresh rate of 60 frames per second, meaning that the image on the screen will be updated every 1/60th of a second. A 144Hz monitor has a refresh rate of 144 frames per second, meaning that the image on the screen will be updated every 1/144th of a second. This means that a 144Hz monitor will be significantly smoother and more responsive compared to a 60Hz monitor.