1) server.Transfer is used for redirecting the user from one page to another this is only for those applications which are running on the same server
Response.Redirect is used for the applications which are running on different server.
2) There is a round trip in Response.Redirect
in the server.Transfer only the data is getting loaded in the same browser means there is no round trip in server.Transfer.
3) Response.Redirect is used in .HTML and .ASPX pages
server.tranfer is used in .ASPX pages only.
4) In response.redirect URL is changed for the new page
in server.transfer the URL remains same.
5) In Response.redirect by default page method is get method means if u want to transfer any data from one page to another then you will have to keep this in query string or session
in server.transfer default method is post method means all the data from previous page get transferred to new page .
6) In server.transfer you will not able to save the history in browser
in Response.redirect the browser history is saved and updated.