What are the key differences between the Canon 15-85mm and the 18-135mm STM lenses?

The key differences between the Canon 15-85mm and the 18-135mm STM lenses are their focal length ranges and maximum apertures. The 15-85mm lens has a wider focal length range, offering more versatility for different shooting situations. On the other hand, the 18-135mm lens has a longer reach, allowing for more zoom capability. Additionally, the 15-85mm lens has a slightly wider maximum aperture, which can result in better low-light performance and shallower depth of field compared to the 18-135mm lens.