Ina Pysch ward, you're watched 24/7, you can be medicated/treated/restrained at any time, you essentially are deemed not mentally suitable to make any decisions about your own well being; emotional, mental or physical. They decide what they can do to you, when they want and how they want. All within the law of course.
In a jail cell, you do have limited privileges, but you are free to move around the yard, the mess and have certain privileges within your own jail cell. You are locked up, but you make your own life, limited to what available. Its still no picnic and would be hell on earth.