Crack Driver Booster 9.1 Pro is an illegal version of the legitimate Driver Booster 9.1 Pro software, which is a tool used to update and manage drivers on a computer. The main difference is that the cracked version bypasses the software’s payment requirements, which is illegal and unethical. It can also introduce security risks and instability, as it may be modified or include malware. The legitimate version, on the other hand, is supported by official updates and customer service.