As KitKat said, PPF is "Paint Protection Film", its primary goal is to protect the paint of a car, whilst generally the idea is to not change the aesthetic of the original paint. Normally they're entirely transparent and colourless to retain the factory paint, sometimes adding a little more depth to them. However, there are some more expensive PPF films that have an aesthetic aspect to it too (coloured, satin look etc). Generally the aim with PPF is to be as unnoticeable as possible but protect the paint. It's thicker than a wrap and has a different installation process. It's a lot more expensive than a wrap (for the same covered area). Often people will just PPF the front bumper, bonnet and wheel arches of a car as they need the most protection.
A wrap's primary goal is purely for aesthetics, changing the look of the car. The best wraps are now paint-like and can even be polished and waxed/ ceramic coated like paint can. They're normally around half the price of a PPF to install roughly. It offers some decent protection from stone chips etc, but not as much as PPF.
I.e:
Generally you'd get PPF to protect the car and have minimal change to the aesthetic.
You'd get a wrap to change the aesthetic of the car but with some additional protection.
For a black roof - a good quality wrap will be better than a PPF and far more economical.