Butterflies? You're talking huge, 30-foot, man-eating butterflies. There is absolutely no way South Vietnam could exist without a DMZ and pervasive US occupation of the South. That was just not going to happen after 1968 ~ 1970.
Yes and no.
Yes, as in a formerly continuous region would be divided into communist and (nominally) democratic states. This is true of the Koreas and would be true of an ATL divided Vietnam.
No, because the (North) Vietnam regime and the North Korea regime have different ideological roots.
Although North Korea is near northern China, the Kim family drew more from Stalinism than Maoism. Juche (the North Korean indigenous communist ideology) was a blend of Uncle Joe's strong-man state, Soviet-style autarky, Soviet-style central planning, with a dash of Confucianism. Kim Il Sung did not subscribe to Maoist guerrilla-style insurgency. He and was more interested in creating an industrial state/personality cult/personal capital generator.
Sure, Ho Chi Minh has a personality cult. However, the VC insurgency, and Ho Chi Minh's leadership style, was very Maoist. Notice also the way in which OTL Vietnam has closely followed Chinese policies. This can best be seen in Vietnam's copy of Deng Xiaoping's market reforms. Should OTL be a guide, North Vietnam might eventually evolve to have a similar, or even better, GDP and nominal market freedom, than South Vietnam.