Etiquette isn’t the same as manners, although they are often used interchangeably.
Etiquette is a prescribed set of rules governing behavior.
Manner is your actual behavior.
Case in point: The rule of etiquette is for men to seat ladies at the dinner table. How the man seats–or doesn’t seat–the lady is manners. Manner of behavior is the way in which we adhere to the rules of etiquette. Manners are the outward display of who you are on the “inside.” Slob on the outside = slob on the inside.
Bad etiquette is using your dinner fork on your salad. Bad manners would be pointing out that someone is using their dinner fork on their salad.
Manners always trumps etiquette.