Is 'sit back' same as 'sit down'?

Native speaker’s answer
Rebecca
No, they're not the same! Here "sit back" instructs the dog where to sit. So rather than sitting in the front of the car, to sit at the "back "of the car. "Sit back" can also be used to tell someone or people to relax while already sitting - to become more comfortable in their chairs. "Sit down" is more of the action of sitting from a standing or other position. Ex: The teacher told us to sit down and take our seats. Ex: I sat forward during the whole movie because it was so good. Ex: Sit back and enjoy the ride.