FORWARD-->
1. THE REQUEST AND RESPONSE OBJECT REMAIN SAME.
2. CONTROL DIRECTLY GOES TO REQUESTED PAGE AT THE POINT 
WHERE FORWARD IS CALLED.
3. REQUEST DISPATCHER IS NEEDED.

SEND REDIRECT:--->
1.NEW REQUEST AND RESPONSE IS GENERATED IN CASE THIS CASE.
2.IN THIS CASE FIRST CONTROL GOES TO CLIENT(BROWSER) AND 
THEN TO REQUESTED PAGE.
3.JUST RESPONSE OBJECT IS NEEDED.

If I am not wrong,
forward() is used to transfer the request within the web 
application whereas sendRedirect() is used to transfer the 
request from one webapplication to another.

FORWARD-->
1. THE REQUEST AND RESPONSE OBJECT REMAIN SAME.
2. CONTROL DIRECTLY GOES TO REQUESTED PAGE AT THE POINT 
WHERE FORWARD IS CALLED.
3. REQUEST DISPATCHER IS NEEDED.
4.forward() is used to transfer the request within the web 
application 

SEND REDIRECT:--->
1.NEW REQUEST AND RESPONSE IS GENERATED IN CASE THIS CASE.
2.IN THIS CASE FIRST CONTROL GOES TO CLIENT(BROWSER) AND 
THEN TO REQUESTED PAGE.
3.JUST RESPONSE OBJECT IS NEEDED.
4.sendRedirect() is used to transfer the request from same 
webapplication  or different webapplication.

FORWARD----->
1) in Forward request and response object be same.
2)IN FORWARD METHOD THE CONTROLLER  DIRECTLY GOES TO  OTHER
PAGE WHEN U CALL THE FORWARD METHOD.
3)FORWARD METHOD USED WITH IN WEBAPPLICATION .
4)In this case  controller goes directly go to request
page.i.e means  does not generated implict reponse go to
browser.
5)U CALL THE FORWARD METHOD JUST NEDDED OBJECT OF
REQUESTDISPACTHER OBJECT

EX:-
RequestDispacher rd=null;
 rd = req.getRequestDispatcher("/WA1");
 rd.forward(req,res);
5)it used small webapplication.

sendredirect:-
1)in sendRedirect()request,reponse object will not be same.
2)in sendRedirect()method the controller did not pass directly.
3)it over come the drawback of forward()(just watch 3 step
in forward()) this method used with in webapplication or
outside of webapplication.
4)In this case first controller goes client browser window
after it will go to request page.i.e means implict reponse
go to browser.
5)u call the sendRedirect()  method  u need a response object.

EX:-
response.sendRedirect("/ServletProject/ValidUser");

forward will happen in the server side,and send redirect
will happen in the client's browser...,and with forward we
can forward with in the same web application,and with send
redirect we can transfer the flow to a different web application