Most Morse code keyers has a mode for emulating bug keys. The figure shows the dot signal (red) obtained at the mechanical contact and the 7026kHz RF waveform (yellow), which is highly undersampled.
The figure shows the same signals but with a mechanical bug key, Vibroplex Blue Racer. Although the dot signals differ in two cases, the movement of your thumb should be almost the same in a sense that you only push the paddle once.
One feature only available to mechanical bug keys is that you can make your dots shorter by retreating your thumb earlier than usual. I do not know if this could really be a feature, but this is something you can not attain by an electronic keyer.