What are the functional differences in display (not input) between an actual 3D display and a 3D object projected onto a 2D display? The only two I can think of

What are the functional differences in display (not input) between an actual 3D display and a 3D object projected onto a 2D display? The only two I can think of are first, being able to use our eyes’ actual depth perception ability instead of the brain imagining it, and second, being able to move your head to get perspective. What are the differences in input? I can think of being able to touch the display more directly. The world is indeed tactile, and I hope such a display would be, too, instead of touching air. No matter how reactive the display is, touching air would not be the same as touching real objects. The problem is that all of these “advantages” require physical movement: moving your hands, arms, and head. Doing this for creative work, which takes a lot of time, would be exhausting. There is a reason why touch screens on desktop computers are not common, even though we have the technology. Your arms get tired. A trackball mouse is a way, way more effective 3D modeling tool than directly manipulating items with your hands. You can work a lot quicker and with a lot less movement.