Fire walls are designed to divide and separate a building, either internally or externally. The intent of the code is that this division creates separate buildings because fire walls are designed for adequate structural stability to preserve wall integrity in case of building construction collapse as a result of a fire on either side of the wall. Think about a parking garage connected to a hospital. The wall separating the two is a fire wall built with the intent of allowing the parking structure to collapse in the event of a fire before collapse of the fire wall.
Fire barriers, on the other hand, carry a Fire-Resistance Rating (FRR) and is intended to compartmentalize a building into smaller fire-resistant zones. They help to control the spread of fire within the same building by dividing it into sections with fire-resistant walls or partitions. Think about a hazardous storage area within a new hospital. Due to the increase in combustible materials within the room, it is separated from the rest of the area by a 1-hour fire barrier.
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