Need of union if we have structure

Question

Difference between union and structure

Answer 1

the size of a structure is the size of all the members in it, while in union it's the biggest member, so think of how that could be of benefit to the memory

Answer 2

As in union its size take the size of biggest member so memory get reduced

Answer 3

For reduction of memory size

Answer 4

why don’t we just use union instead if structure then?

Answer 5

Diffrence is only memory allocation