The difference between Milwaukee's FUEL range and their standard brushless M18 tools is that FUEL has a much more powerful POWERSTATE brushless motor. According to Milwaukee, it is 4 times more powerful! The POWERSTATE Brushless Motor delivers more application speed, torque and durability in a more compact form. Overall, M18 FUEL tools are worth the investment for professionals and daily users who require top-tier performance, durability, and advanced features in their tools. For weekend warriors and DIYers with lighter tool usage, standard M18 tools may provide sufficient functionality at a more budget-friendly price point. The M18 tools are 18 volts while M12 are 12 volts. All new Milwaukee compact tools have POWERSTATE™ brushless electric motor technology supported by Milwaukee REDLINK Plus™ energy source intelligence. One of the great things about Milwaukee's M18 and M18 Fuel systems is that all the tools work on the same RedLithium M18 batteries . So, no matter if you use Milwaukee brushed tools, compact tools, or their flagship ONE-KEY models , all M18 tools and products run on the same 18V RedLithiuum batteries. Delivering unrivalled performance in a compact structure, all M18 FUEL™ products feature three Milwaukee® exclusive innovations: The POWERSTATE™ Brushless Motor, REDLITHIUM™ Battery Pack and REDLINK PLUS™ Intelligence Hardware and Software. These deliver unmatched power, run-time and durability on the jobsite.