Answer:
The main difference between Vietnam war and the other previous US war was that the Vietnam war was a civil war.
Step-by-step explanation:
The Vietnam war was the second Indochina War officially fought between North Vietnam and South Vietnam. The U.S was allied to South Vietnam as an anti-communist alliance. At the time, the U.S. had a treaty obligation under SEATO (Southeast Asia Treaty Organization) to help the South Vietnamese. It was a war going on inside a country that lasted for about nineteen years. The justification that U.S. had for the military involvement in the war was because the North Vietnamese had fired on the U.S. ships in International waters.