What are the two subdivisions of terminal ballistics?

The two subdivisions of terminal ballistics are internal ballistics and external ballistics. Internal ballistics focuses on the behavior of a projectile within the firearm, including the ignition of the propellant and the projectile's travel through the barrel. External ballistics deals with the projectile's flight through the air after it leaves the barrel, considering factors such as trajectory, velocity, and environmental influences. Together, these subdivisions help in understanding a projectile's performance and effects upon impact.