Circuits
240v circuits
Whether the circuit is for a spa, air conditioner, washer or dryer, air compressor, or a welder. A circuit is much different from the rest of the receptacles in your home. Most of the time powering up an appliance that otherwise installed at 120V would use up twice as many amps in your panel. A 240V circuit takes up two spaces in your panel and requires a 2 pole breaker.
Dedicated circuit
A dedicated circuit is a circuit that usually serves one purpose. Whether it is for your home computer equipment or your microwave, the device connected either uses up the whole circuits power or is something the home owner might not want to share power with the rest of the house.