The difference between NASM certification and ACE certification is that the former is a more generic certification for personal trainers. The latter is a specific certification for those who want to work in the business world. What you will learn in the NASM education is how to work with clients, how to create an effective workout plan, how to motivate your clients, how to use resistance training, how to manage your time as a personal trainer and how to develop your business skills. On the other hand, the ACE certification will give you a better understanding of what a personal trainer should know when working in corporate fitness.