The question is a little vague, but I would say that while the South was able to entertain the favor of several European nations, most notably Britain, she was still unable to convince any foreign powers to fight on her behalf. So even if the South was better at diplomacy, I wouldn't call it an advantage because in the end it brought no significant foreign aid.
The North had two disadvantages. As the invading army, they lacked detailed knowledge of the local terrain, and most of the experienced professional officers were Southern, meaning that, at the beginning of the war, the North lacked leadership.
There is NO North Vietnam & South Vietnam today (and there hasn't been a north & south for over 30 years; when the north conquered the south, ending the war in 1975). Today's Communist Vietnam is President Triet.
The only real weakness IN THE BEGINNING of the war was the North's leadership. The North had the bigger population of males, a bigger navy, and quite obviously to anyone who could read and write (in those days)...the North had a giant of industrial might, when compared to the agricultural South.
It started on the south side but when they meet, they cross over toward the north side.
after North Vietnamese troops took over Saigon in 1975.
The South had better generals than the North did at the time.
The South was fighting in its own territory.
wealth and manpower
The home field advantage
The North had a 81% Advantage in bank deposits to indicate for the North over the South who had only 19%.
The US had been split into the Union (North) and the Confederacy (South)
The south had a labor advantage over the north
No advantage. SC is backwards - NC is not. There is no comparison!
One under appreciated advantage was the railway system, the north had a much vaster railway network that they contiuned to add to throughout the war and they used it to devestating effect. Where as the south didn't extend theirs anywhere near enough. The result being that the north could move troops and supplies around alot faster than the south. Not necessarily a war winner, but a massive advantage, no the less.
The North had the factories capable of making supplies and equipment for war.
The South had superior generals. It also had a powerful patriotism and a belief in the justice of its cause.
The quality of its Generals, and a powerful mission-imperative: to defend the homeland against the invader.