When can the Native resolution not be actual resolution?

Question

I was writing some programs that were sensitive to screen size, and for the life of me I cannot figure out how this is possible. The display settings in the nvidia and windows control panel are set to 1920x1200 (native), while GeForce experience and www.whatismyscreenresolution.com both report 1280x800. It is like the actual resolution differs from that which is set. How is this possible?

Answer 1

OK after a lot of digging, apparently the resolution is changed behind the scenes if you have selected "Larger" under Right Click Desktop --> Personalize --> Display. I set this to "Smaller (default)" and everything is reporting correctly now. I'm not sure, but somehow Windows 7 must change the resolution by a factor of 1.5 behind the scenes if you choose the 150% option.