Drum Sander versus Wide Belt is a real sander paradox. While a belt sander means a hand-held power tool, not so with a wide belt sander. In which case you should also know that industrial wide belt sanders are for finishing rather than "working" timber.

Technically a drum sander reduces the thickness of stock but might not be able to remove much in a pass. It would take time getting rid of enough material to make it worthwhile. When you need to reduce the thickness of stock then the drum sander may not be the best option. Which is why wide belt sanders are preferred. Wide belt with multiple belts and selectable drums are better, but very expensive.

A good option could be the single belt, wide belt sander. Using pneumatic air power for maintain belt alignment, they also have electric eyes and servo control. Not only do they save time but are easy to use especially for getting super fine veneer.

For other applications drum sanders are good. The 12 inch drum is a nice compromise but they are hard to get and also the belts are expensive. Further these sanders need a lot of power, especially for wide surface sanding. Which is why many of these sanders have onboard amp meters.

The industrial twin drum sander working together is another option. The drums oscillate back and forth, and can be used alternatively. You can have low grit paper on the first drum and finer finish grit on the other drum. However these machines are quite large and consume a large footprint of workshop space.

Modern sanders use rubber conveyor belts. You see this on both the wide belt sanders as well as the drum sanders. They also have supportive platen underneath. With drum sanders it appears you have to contend with the paper and wood burn if heat is not removed from the process.

The redeeming feature of the wide belt sander is its ability to run cool under continuous full loading. Which brings us back to the paradox – what is better - the wide belt sander or a good drum sander? Each is actually accomplished for different woodworking machines for different sander solutions.