Belt and roller conveyors both move goods horizontally, and for many projects either will work. The choice usually becomes obvious once four questions are answered honestly.
Question 1 — can the product support itself?
Roller conveyors need a rigid, flat, reasonably heavy underside. Bags, trays, small parts and products with a soft or irregular base need a belt, which supports the whole footprint continuously.
Question 2 — will products accumulate?
Both can accumulate, but differently. Roller conveyors accumulate naturally with low back-pressure and are cheap to zone mechanically. Belt conveyors need accumulation rollers or slip-strip sections. For long buffering runs, roller is normally the lower-cost answer.
Question 3 — does the route bend or climb?
Roller curves are simple and reliable; belt curves need tapered rollers or a curve belt. Gradients suit belt better — a belt can climb 15–20° with a cleated or rough-top surface, where rollers generally need a powered or gravity decline.
Question 4 — what does maintenance look like?
Roller conveyors have many bearings but no belt to track, so they tolerate misalignment and dirty environments well. Belt conveyors have one tracking adjustment to watch and a belt that eventually needs replacing, but far fewer wearing parts.
In practice many lines use both: roller for carton transport and buffering, belt where the product is small, soft or must be held in position. Sharing one frame system keeps the interface simple.