what is the basic difference between stack and queue?

Stack is a LIFO (last in first out) data structure. The associated link to wikipedia contains detailed description and examples.

Queue is a FIFO (first in first out) data structure. The associated link to wikipedia contains detailed description and examples.

Imagine a stack of paper. The last piece put into the stack is on the top, so it is the first one to come out. This is LIFO. Adding a piece of paper is called "pushing", and removing a piece of paper is called "popping".

Imagine a queue at the store. The first person in line is the first person to get out of line. This is FIFO. A person getting into line is "enqueued", and a person getting out of line is "dequeued".