It’s semantics. They both have (or have the option of) all four wheels driving the vehicle.
You’ll get some people stating oversimplified definitions such as being able to select 2 or 4 wheel drive or having locking differentials. But these are only features that might be more likely on a vehicle marketed as 4WD.
The actual truth is that there isn’t a set in stone difference. Select a vehicle based on the characteristics or features you need, not the terminology selected by the marketing department.
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