In the former case, I can see LEOs saying, "look, go to court and get papers" and in the latter case, LEOs dragging the trespassers out into the street so you don't shoot them first.
No, there is no difference.
Property can be vacant for a number of legitimate reasons nor is there any way of telling how long it’s been vacant for.
Besides, just cause it’s vacant at the moment, is NO excuse ever to steal it.
Would you feel that way if it were YOUR property? Or your car? Well, nobody was driving it at the moment so I took it.