What is the major difference between a vector and a stack?

Question

Both act like a stack. Both have push and pop operations.

Is the difference in some memory layouts?

Answer 1

stack is a stack. It can only push and pop. A vector can do other things, like insert into the middle. This increases flexibility, but reduces guarantees.

For example, for a stack, if you push A then B onto the back then you are guaranteed that they will be removed in the order B, then A. vector doesn't guarantee that.