"...how is it that a 1920x1080p image looks better on the camera's screen low resolution screen than on my laptop?"
If by "better" you mean sharpness, realize that sharpness is not the same as detail. Your little camera display is down-sampling the HD image and may sharpen it in the process. You can get the same effect in software on your computer. Also, how the footage looks on your computer will depend on what software you use to play it. Basically you're comparing apples and oranges when you use two different players (the one in your camera and the one on your computer).
Really, the best way to evaluate footage is at full resolution, with one-to-one pixel correspondence, so there's no re-sizing going on. That would mean viewing 1920x1080 footage on a 1920x1080 display (or a higher-res display using a 1920x1080 sized part of the screen).