What is Difference between "Use controller rotation" and "Set Actor Rotation"

Thanks for answer!

result of “use controller rotation yaw” and “set actor rotation (actor rotation (pitch, roll) + control rotation yaw)” was seemed same.
so, i’m really wondering that what is difference between them?
is it just different way of setting character rotation? or something different?

they are as different as a keyboard is different from a mouse

One is prebuild behaviour that tells your Movement Component to use Controllers Rotation. (you dont have to set it on tick, one time on begin play or via defaults is enough)

The other one sets your Rotation of the Actor by Hand → whatever you feed it with.