By the end of this journey, however, your main character or characters should be different because of the experience. If you don’t’ show the possibility of moral transformation or an increase in wisdom in your protagonist(s), there really is no point in writing the screenplay at all, because one of the most fundamental human principles is that human beings do have the capacity to change.
This is the character arc. But is there a difference between growth and change? I say yes; it’s not just semantics.
Take the 1957 drama Sweet Smell of Success. The protagonist and anti-hero Sidney Falco (Tony Curtis) does not change in the end. He’s still the same guy: “a cookie full of arsenic” as the antagonist J.J. Hunsecker (Burt Lancaster) describes him; however, he does learn something. Knowledge is growth, and he does grow within the small fishbowl world he operates in, but there is little hope that he’ll live his life differently tomorrow. Susan Hunsecker (Susan Harrison), on the other hand, the meek, intimidated, and terrified little sister to J.J. finally stands up for herself in the end, changing into a self-empowered, confident, strong woman.
So knowledge is growth, but acting upon that knowledge is change. You need at least one.