About the simulation
The simulation shows the fundamental optical differences
between different cameras based on their sensor size and maximum apertures.
It doesn't compare differences in contrast, dynamic range, handling all those other factors, there are plently of camera websites which already do that, e.g. Digital Photography Review
The noise level is exaggerated to be more visible in the small window above. The relative
noise between cameras based solely on the ISO and sensor size, and doesn't account for differences in sensor sensitivity. Absolute aperture sizes vary far more than sensor sensitivity, so the simulation is still very useful despite this ommission. For some actual camera data taking into account sensor sensitivities see DXO Mark
The noise here has no processing applied. Real digital cameras will apply noise reduction when creating JPEG images, which creates a smoother image but with some loss of detail.
Each scene is composed of one or two planes which can be defocussed (blurred) independently. This is the minimum required to demonstate depth of field. Of course a real scene can be composed of objects with an infinite range of distances from the camera.
Bokeh is the shape of a point of light which is out of focus. In this simulation they are square which makes it fast for a computer to calculate. In a real camera they can be a variety of shapes from circular to polygonal, but I've never seen square ones!
The maximum aperture at a given focal length is linearly interpolated based on the values given at each extreme of the zoom range. In a real camera the relationship isn't linear so the maximum aperture values within the middle of the zoom range may be slightly off.