I am having trouble understanding the difference between free will and what has been decreed for us. Allah SWT is the All Knowing and He knows where our fate will take us, but can our ultimate fate and outcome change from the actions we do?

Of course, our fate is ultimately in our hands in the sense that we have to choose, and those choices will have consequences. We can even change our minds and choose differently, which will then alter the course of our life. Regardless, Allah, with His infinite knowledge knows what we will choose and which course we will take even before we do so.