If you can’t tell the difference, you need to do more research. The differences are obvious, even at a glance. A commuter is designed for (doh) commuting. It has an upright seating position which is comfortable at lower speeds. It is easier to thread through traffic and it (usually) doesn’t have a fairing, or if it does, it’s a small one. They’re sometimes called naked bikes. Sport bikes have fairings and are the opposite of the above, designed for high-speed, knee-dragging fun. You can commute on a sportbike, but at a cost to your wrists and back. You can also have fun on a commuter. Commuters usually give more mileage because their engines are in a lower state of tune. Neither of them are outright ‘best’; commuters are best for commuting, sportbikes are best for speed.