Looking at my main panel I see to bus bars on each side of the breakers. The ground is attached to the one on the right. I see green and white wires attached to the bars on both sides. There is a bridge at the bottom connecting both. It looks like there is no difference between neutral and ground. Is this normal?
In wiring the subpanel does it matter where the ground is attached i.e. right or left bus on the main?

thanks