Ceramic is often “layered” via Multiple coats in order to build up thickness and protection. Not designed to protect against impacts etc. but it does preserve paint if paint correction was done, i.e. a full cut and buff, as well as add barrier to keep debris from accumulating on the surface.
PPF is good for road car to protect against impacts and debris causing chips and scratches.
Also note that people do ceramic OVER PPF in order to protect things from STICKING to the PPF and make it easier to clean etc.