:OK, so I did some research, dug up the species description, and the bad news is that these species can't be distinguished on the basis on images alone.  The distinction is based on counting the number of ventral scales, as well as subtleties from head scalation.  C. cerastes has 139-149 ventrals in males and 143-151 ventrals in females, while C. gasperettii males have 154-162 ventral and females have 153-172.  Basically, in order to distinguish them, you'd need to take them to a museum.  However, I wouldn't recommend this, as the leading cause of snakebite is people trying to capture the snake.  At the end of the day, they're not visually distinguishable to anyone but a professional.  Based on range, I suspect yours is C. gasperettii, but only a museum can tell for sure.