Energy is energy. If you have a 2kW load, the energy it will use will be 2kW AC or DC. But consumption is also a factor of load and efficiency. Conversion from one form of electricity flow to the other costs efficiency. If your load is AC and the source is AC, then that will be MUCH higher efficiency than if your load is AC and the source is DC, and vice versa.
So frame your question with specifics, unless this is a homework assignment, in which case do your own work.
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