I personally wouldn't define it as the ability to act differently but even if that was the definition it would still imply free will. Normal definition of free will would be us having a choice between this or that. However, I'll use your definition. We can act differently. Suppose I drive home from a place and I take the same route. At times I did act differently. Sometimes the normal route I took had construction and it was closed. Other times, I felt like driving a different way just for a different scenery or whatever. I simply acted how I wished for whatever reason because sometimes not acting differently can be boring. One can even choose to be happy over being sad. It's often taught as a coping mechanism or changing your point of view of how you perceive things. Let me explain. When I lost my grandma I was a wreck. It affected my education and work. When my other grandma died I decided not to repeat the cycle. I took a quick day of grief and focused on positive things. I was up in good spirits planning a party. Since then I prefer to limit how long I remain sad, worried, and all other negative things.