How did the technology of the Vietnam war differ from previous wars?

The Vietnam War was the only war, during the COLD WAR, in which the United States failed in preventing a non-communist country from falling to the communist powers. The US successfully stopped the communists at the 38th Parallel in the Korean War (1950-1953). The Axis Powers of WWII were sounded defeated by the US & Allies. The Central Powers of WWI were defeated by the US & Allies.