Which floor sander do I need to tidy a room and to strip paint off a deck?
The Square Buff Floor Sander is a big version of a palm sander. In other words, you attach a piece of sanding paper and the machine shakes it in some pattern.

The Floor Sander is a big version of a belt sander. Unlike a belt sander (where the sand paper comes as strips with the ends glued) the large version just takes an ordinary rectangular sheet of sanding paper. The paper is wrapped around a drum and is inserted in a notch in the cylinder to stay put.

The U-Stand Pro Random Orbit Floor Sander takes a flat sheet of sanding paper, but one cut in a circle. It is not advised to use this machine by someone without some experience, because it can easily spin out of control, damaging the floor. It must be held steady.

To summarize, for minor marks in the hardwood, use the Square Buff Floor Sander. For major marks, use the Floor Sander. Either way remember to keep moving, and steadily, to get a uniform layer off.