How is a fixed pulley different from a movable pulley?

A fixed pulley is different from a movable pulley because a movable pulley has one end of the rope attached to it fixed on an unmoving object. The pulley is free to move with the rope. You pull the other end of the rope. Also, a movable pulley multiplies the applied force (effort force) and therefore has more mechanical advantage. A fixed pulley is attached to something that doesn't move, while one end of the rope is holding the weight, while the other is for pulling.
A fixed pulley confers no mechanical advantage, but will convert motion in one direction into another direction.

A movable pulley system, if the pulleys change their distance from each other, will confer a mechanical advantage.