Reunion refers to the act of coming together again after a period of separation. It is often used to describe gatherings of family, friends, or former colleagues.
Union refers to the state of being joined or combined. It can be used in various contexts, such as:
* Labor Union: An organization of workers who unite to improve their working conditions and wages.
* Political Union: A group of states or countries that come together under a common government.
* Marriage Union: The joining of two individuals in a legal and social partnership.
Therefore, while both words imply a joining or coming together, reunion specifically refers to a gathering after separation, while union has a broader meaning that encompasses the state of being joined or combined.