Answer:
Union between sets (lets call them A and B) is when all of the elements in set A and B are together. For example, say set A is x, y, z, and set B is l, m, n. A U B would be l, m, n, x, y, z.
Intersection between sets is only for shared elements in each set. For example, if set A is a, b, c, x and set B is x, y, z, a, then the intersection of sets A and B is a, x