The person is "triggered" and effectively operating on autopilot without a pause between the stimulus and the reaction.

Conversely, a mature scream is a highly conscious, deliberate act of somatic processing. It is the adult realizing that cognitive processing has reached its limit and the physical body needs to expel trapped energy. How to Stop Screaming and Start Parenting Effectively

Often directed at others as a weapon to control, intimidate, or project internal pain.

To understand the "mature scream," we must first look at its primal roots. The human scream is one of our most evolutionarily conserved vocalizations.