Final answer:
The Cold War involved the United States and the Soviet Union as the primary nations in a global struggle for supremacy, which included technological, ideological, and military aspects. Their conflict influenced additional nations to align with either the NATO bloc or the Warsaw Pact. World War I's primary combatants were the Allied Powers and the Central Powers, with many other nations joining the conflicting alliances.
Step-by-step explanation:
The two primary nations involved in the Cold War conflict were the United States and the Soviet Union. This global rivalry extended into all aspects of society, including technological advancements like the space race, socio-political spheres with efforts to suppress communist influences, and numerous proxy wars in other nations such as the Vietnam War and the conflict in Afghanistan.
During World War I, the main nations involved were the Allied Powers, consisting of Great Britain, France, and Russia, and the Central Powers, comprised of Germany, Austria-Hungary, and initially Italy. Following this era, the United States and the Soviet Union emerged as the last two superpowers, leading to the Cold War. Other nations that joined in support or opposition to these superpowers did so through alliances such as NATO, the Warsaw Pact, and varying levels of involvement in proxy wars across the globe.
The Cold War saw the establishment of rival blocs, with capitalist countries aligning with the United States and socialist countries aligning with the USSR. Many nations received financial aid, military support, and technical advice to support one side or the other for various reasons, including ideological alignment and the opportunity for developmental aid.