PTSD comes from witnessing or experiencing a singular traumatic event. This could be something like a car crash, a natural disaster, a sexual assault, a wartime atrocity, or a violent act.
CPTSD comes from long-term repeated trauma. CPTSD often develops in those who have been abused by someone who was in a caregiver or protector role, often developing in children. Examples include survivors of ongoing childhood sexual assault by a relative or caregiver and survivors of human trafficking. Other long-term traumas that can result in CPTSD include (but aren’t limited to) childhood neglect, ongoing/long-term physical, sexual, or emotional abuse, living in an area of war, or being a prisoner of war.