I'm preparing to provide new wiring to a sizable addition to a log home. Prior to beginning the new work I mapped my existing circuits thinking it best to correct any potential overloads in the existing panel/circuit design before introducing any new problems on my own.

Decided to make a few changes by running 3 new 20 Amp dedicated circuits to service a garbage disposer, a microwave, and a utility room with a washer/dryer (gas) - all are currently on shared circuits. I was surprised when I opened my main service panel and found that neutral and ground wires from existing circuits are interchangeably attached to either the neutral or the ground bus. In many cases both the ground and the neutral from a respective circuit are attached to one or the other of the buses under under the same screw.

I have read that the ground and the neutral bus are generally bonded within the main service panel. Does this mean that there is really no difference between the ground and neutral bus within a main service panel? If I add circuits can I simply connect the hot to the breaker and both the white and bare copper ground to one or both of the neutral/ground bus?

I expected things to be far more orderly.