The central idea is the same as the main idea. Most of the time, the main idea is mentioned in the Title. Without reading the essay, I do not know what the central/main idea is.
Free will is the freedom to make your own choices. You get to choose your occupation, clothes, things like that. Fate is where things at meant for you. You might meet a stranger and they could change your life. You could get in a traffic jam but when you get to where you were going it turns out that if you had been there on time, you would’ve been stuck in a robbery. However, fate and free will can go hand in hand. Your choices could lead you to your fate.
