Cruising Cabin House Electrical Functions

I’m preparing for a few days camping in Oregon at their state parks. Since they have plugins, I thought I would get the van ready to get power. In the small side door, there is a plug in with a pattern I have not seen. There is a cord that adapts to it along with a grounding spike. When I plug it in the electrical outlets work but not the fridge or any other house functions. Everything seems to run off the house battery. 

Is that the same in your cruising cabin?

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