Actually, the North invaded South Vietnam with more tanks, more modern tanks, and with tanks almost 4x the size of Germany’s tank army that conquered Belgium, Denmark and France in less time with fewer casualties.
Heinz Guderian would have well-recognized the final assault on South Vietnam as using the sort of Blitzkrieg tactics he developed.
We defeated the insurgency in 1968, irregular warfare by the north from 68-71 and the helped the ARVN beat the first conventional invasion in 1972. When Congress cut off support, the North attacked with four Corps in 1974, including armor, artillery and air support. It was too much for the ARVN.