Doesn't resolution also affect real estate? e.g .able to display more full content windows on the desktop etc.
Yes, more resolution = more real state.
It depends on how you use the resolution. Native LCD resolution, physical screen size, scaling factor, (simulated) real estate, text/object size, and amount of detail in text are inter-related.
Consider, for instance three 24" monitors:
1. One with a native resolution of 1920x1080 pixels, running at native resolution.
2. One with a native resolution of 3840x2160 pixels, running at native resolution.
3. One with a native resolution of 3840x2160 pixels, running at a scaling factor of 2x.
Monitor 2 will have four times as much "real estate" as Monitors 1 and 3, but text will only be 1/4th of the size (1/2 the width, 1/2 the height). This may make things next to impossible to read.
Monitor 3 will have the same amount of 'real estate" as Monitor 1, but will have extra pixels to devote to drawing the same-sized text in more detail.
If you make Monitor 2 a 32", 3840x2160 pixel monitor, that will increase text size a bit, but the letters are still going to be smaller than they would be on Monitors 1 and 3. You'd need a 48" screen to dedicate all of the pixels to "real estate" (scaling factor 1x) without seeing any shrinkage in the size of text.