The resolution of the actual image that is displayed on the screen can't be any higher than the resolution of the monitor.
Everything else being equal, a 4K monitor is going to be sharper/clearer than a 1440p or 1080p monitor. Whether the difference is actually noticeable during real world use depends on screen size, viewing distance, and your eyesight.
Resolution an panel type affect the image in completely different ways. An IPS panel will have better colors and viewing angles than a TN panel. A higher resolution display will be clearer/sharper.