While both methods help increase fire resistance, there is a slight difference between fireproofing a building and adding firestopping as a preventative measure.
Fireproofing is a method that includes spraying down or painting fire susceptible materials with a fire resistant coating to increase longevity and temperature resistance.
Firestopping is specifically applied to entrances, exits, and walls that are combined with all rooms in a building. This prevents a fire from spreading if it occurs, so damage is minimal by the time the fire is put out.