It might involve similar regions, such as the Fusiform Face Area (FFA), but people with prosopagnosia don't necessarily have difficulty with identifying facial emotions; what they have difficulty with is in distinguishing and remembering faces from each other. It's a bit like the way most of us couldn't tell one sheep from another in a flock.

Prosopagnosics tend to rely on things like voice, gait, haircuts, facial hair, and name badges.