There hasn't been a study comparing just these two groups under equal circumstances. A recent Canadian study did identify height as a risk factor in men. In the Canadian study, weight was not linked to back pain or injury in either men or women. However, other studies have reported increased back pain in overweight adults.
Risk factors for back pain remain a mystery. Despite many studies, researchers really don't know what puts one person at greater risk than another. Some say smoking is a risk factor while other say it's not. Age (older) may put us at risk, but this isn't proven.
Most agree that personal stress and other psychologic or social issues are connected with back pain. More studies are needed to help us understand risks for back pain. The next step is preventing it.