DC power is the type of electricity stored in batteries, which provides a steady flow of current in one direction. In a van, DC power is typically used for 12V systems like lights, fans, and appliances. It’s direct from the van's battery and is perfect for low-voltage devices.

AC power on the other hand, is the type of electricity supplied by the grid (think of the power in your home). AC power switches direction regularly and is used by most household appliances, like refrigerators, microwaves, and power tools. In a van, AC power is usually accessed through an inverter, which converts the DC power from the battery to AC power, allowing you to run larger appliances. The Inverter also is the channel that energy flows and charges the battery from the Grid (shore power). 

In short, DC is great for low-power systems and charging, while AC is essential for running bigger appliances.