The retention of guns on jets.
The only big lesson learned was North Vietnam was not invaded. During the Korean War, N. Korea was invaded; that brought in Red China. That strategy was not repeated in the Viet War.
We won.
The former NORTH Vietnam won the war; they are known as just Vietnam today.
The anti-war protesters of the Vietnam era had a personal stake in their protest...they might get drafted! Today's protester doesn't have that personal stake.
The US is not at war with Iraq.
The website, "Vietnam War casualties" might be helpful.
The Vietnam War might have been avoided, if communism had not been involved.
It is generally seen as an American failure in war.
Laos may not be as industrialized as Vietnam is; Vietnam learned much from the US.
For the typical citizen at large: 1. An all volunteer military (no more fear of being inducted into the service). 2. Voting age lowered to age 18 (used to be 21). For the military population: 1. The F22 Raptor still has guns on it thanks to the Vietnam War. 2. All armies now use the assault rifle (pioneered in the Vietnam War). 3. The M1 Abrams MBT (Main Battle Tank) was pioneered on the combat experience obtained from the M48 Patton's combat experience in Vietnam, among other conflicts. 4. Today's Kevlar helmet is based upon lessons learned in Vietnam combat. 5. Today's Blackhawk helicopter is based upon lessons learned from the UH-1 Hueys (Iroquois) combat experience in Vietnam. Today's AH-64 Apache helicopter gunship is a direct descendant of the Vietnam AH-1 Cobra attack chopper. 6. The A-10 Warthog took some of it's design lessons from the A1 Skyraider's (code named Sandy and Spad) experience in the Vietnam War. 7. Today's USN riverine forces took their ideas directly from the USNs "Brown Water Navys" riverine forces in Vietnam. Just a few examples.
Vietnam reunited in 1976 after the end of the Vietnam war, South Vietnam (democratic side) losing to North Vietnam (communist side).