Capitulation
the action of surrendering or ceasing to resist an opponent or demand.
Surrender is essentially used when a person or small amount of troops surrender.
Capitulation is more equal to signing a treaty.
Capitulation is an agreement in time of war for the surrender to a hostile armed force of a particular body of troops, a town or a territory
But they can be used interchangeably but most will say surrender since 95% of people may not know capitulation.