Is 1920x1080 a resolution?
Full HD is just another term for 1080p or 1920x1080, and those are all ways of referring to the same resolution. By contrast, 4K has a resolution of 3840x2160. That's a lot more pixels in the overall image — totaling over 8 million pixels. As always, the higher the resolution, the sharper the picture will be.
Is 1920x1080 full screen?
That monitor has a native resolution of 1920 x 1080 at 75 Hz and so, should be full screen at that resolution . . . If your screen is not full screen, do you have a black border on the sides of your screen?