what is the difference between request and session scope in spring?

Your understanding is correct. However I would like to add something

Whereas if the scope is defined as session for the bean, if a user makes a request for a web page more than once, then on every request same bean would be returned.

I would change it as "Whereas if the scope is defined as session for the bean, if a user makes a request for a web page more than once, then on every request same bean would be returned, as long as the requests are within the same user session and made from a client which is capable of maintaining the session (You can't expect the curl to maintain the usersession unless you pass the cookie/session identifier header)."

Session Scope -- when the scope is session,the values of formbean(form data) would be available throughout the session. it will not destroyed until session timeout up or session destroyed.

Request Scope -- when the scope is request,the values of formbean(form data) would be available for the current request. it will refresh on every request of same user/different user.

because http is stateless protocol