There is a total design difference.
One of the big things is the way they are made for shunning water. The residential windows are made to be stationary. In a typical horizontal slider application, they seal water and air by means of a finned weatherstrip and also some have soft rubber gaskets. Water runs downhill so they work well for that.
Take that same window and spray water at 60 miles an hour sideways and water will migrate in through the interlock bar, especially top and bottom.
Also, the closing / locking mechanisms on a stick and bricks window are not made for movement. Many have a drop lock or swivel catch only and it would move around during travel. RV widows are designed to stay locked while going down the road.
Also, as bumpy mentioned, the size of the walls. Residential windows are physically wider and would not fit the wall thickness. Our typical RV wall is less than half the thickness of the standard 2X4 residential wall.
There are a number of other things too, but suffice to say, this is simply not a good idea.
