Colonel Harry Summers, a Vietnam veteran and author, once recounted a conversation he had with his North Vietnamese Army counterpart a week before the fall of Saigon. He said, “You know, you never beat us Americans on the battlefield.” “That may be so”, the NVA colonel replied. “but it is also irrelevant”.
Conventional wars pivot around geographical resources. Be it capture of a ground of tactical importance, or victory at a theatre level, conventional war aims to destroy the enemy’s troops & resources and dominate areas previously controlled by the enemy. That is the pattern of conventional wars.
An insurgency, on the other hand, is a competition between the insurgent and the government or support of the local population. Superior kinetic energy and operational intelligence enabled Americans to win almost every battle in Vietnam but that very force and ruthlessness alienated the population, losing their support. That is why the NVA won the war, even though it lost most battles in purely military terms.
What makes an insurgency different
The centre of gravity in an insurgency is always the local population because an insurgency is essentially a political movement.