The Arduino picture area allows for the digital inputs and outputs to be displayed along with the Analog input and output values. The digital pins are defined up to D53 for the Mega and D13 for the Uno.
The Analog Pins are defined as A0 to A5 for the Uno with A0 equal to 14. Other boards are setup according to the Arduino configuration.
The Simulator also allows for custom boards to be setup.