What is the different between cookies and session in php

Cookies are stored in client machine and sessions are stored in server machines.

What is the different between print and echo?
Echo is a construct. It takes command only. It takes multiple parameters and faster than print. Whereas print is also construct and function but print does not take multiple parameters it will return true (1) or false (2) or some values.
Echo is just a statement and not a function and doesn’t return a value or it justs prints a value whereas print () is a function, which prints a value and also returns a values.

How can we submit a form without submit button?

With javascript
With header function of PHP. Header (“location: $ur;”)