Alec Baldwin is an actor/producer who was given a loaded weapon in error as a prop on a film set.
While Baldwin is definitely civilly and possibly criminally responsible as producer for the incredibly sloppy weapons handling on that set, as an actor he was given a prop and told it was safe.
Kim Potter was a sworn and trained police officer, she is expected to be able to identify the weapon she is selecting and to not mistake a pistol for a taser.
She is held to a higher standard, and rightly so.