How do professional ceramic coatings compare to retail ceramic coatings?
Of the named brands, they don't really compare at all. Most of the products we are aware or have tried are synthetic waxes which contain ceramic, and therefore they are best compared to other waxes. (Waxes have contained ceramic beads as diffusers to hide scratches for decades).
Professional products are not user-friendly and can be very unforgiving, which is one of the many reasons they aren't sold to general public. It would be irresponsible for any company to sell products to the general public which could go horribly wrong and damage their cars, and no doubt lead to a string of lawsuits. However, it is likely that there are manufacturers out there who haven't been able to successfully compete in the professional market, who are selling ceramic coatings to the public.