The Viet Cong was better at fighting a guerrilla warfare, while the US was better at fighting open terrain and urban combat.
You must remember that the US fought the Viet Cong during the Vietnam war, in which the country was (& still mostly is) surrounded by dense jungles, which the US rarely fought in following WW2. This led to a deficit in the US military, as few had any experience in fighting inside the jungle, while the Viet Cong was fighting on their home turf, which meant that they knew the area a lot more better. This led to the US using harmful chemical weapons to clear the land (usually Agent Orange), but advances in the jungle was limited.
However, when fighting in urban combat, the US excelled in such a way that they were able to almost crush the Viet Cong. However, because of media misrepresentation, and US public opinion, the US public was given the information that they were actually losing, and so they demanded a withdrawal from the war. This occurred, and South Vietnam fell to the communist regime soon after.
tenochtitlan (also spelled tenochtitlán), located on an island near the western shore of lake texcoco in central mexico, was the capital city and religious centre of the aztec civilization. the traditional founding date of the city was 1345 ce and it remained the most important aztec centre until its destruction at the hands of the conquering spanish led by hernán cortés in 1521 ce, which led to the final collapse of the aztec empire.