As the title suggests, fire protection is classified into two parts: active and passive. Though they are distinct, they are meant to work in unison in a fire emergency. But first some definitions.
Active fire protection are those fire prevention systems that require an action to work properly. Actions would include doing something physically or manually. Pulling a fire alarm or sprinkler system and using a fire extinguisher would be examples. Note that these measures do not always solve the problem (if they did we wouldn’t need firemen).
Passive systems are those components that use resistance to contain fire. This would include fire resistant walls, fire detectors, dampers which keep smoke from spreading through the air ducts, fire doors which help compartmentalize a room or building, and fire resistant floors. Additionally, multi story buildings use lighted Exit signs to help escape efforts.
As you can tell, neither one works completely. They exist in unison in the event one component or more stops working. For instance, in the winter water sprinkler systems can freeze. Sometimes firefighters are delayed from arriving at a fire because of inclement weather. Active systems work positively toward putting out the fire while passive systems contain it.
The issue isn’t as clear cut as you might think though. In places where there are a lot of high rise buildings, compartmentalization can become the de facto primary means of containing a fire. A lot of study has been put into this field, and much money has been put into creating “faultless” fire alert systems which are at minimum meant to prevent the loss of life.