Server. Transfer sends information from one web request to another, all on the server side. A response is not sent to the browser. On the other hand, Response.Redirect sends an HTTP 302 message to the browser and causes a redirect in the browser.

In ASP.NET, both Server.Transfer and Response.Redirect are used for page redirection, but they operate differently:

Server.Transfer:
- Server.Transfer transfers control from one page to another on the server side.
- The URL in the browser remains the same.
- It is faster compared to Response.Redirect as it avoids the round-trip between the client and the server.
- It can transfer data between pages using HttpContext.Current.Items or Server.Transfer method’s second parameter.
- It can only transfer control within the same application.
Response.Redirect:
- Response.Redirect redirects the user’s browser to a different page or URL.
- The URL in the browser changes to the new page’s URL.
- It is slower compared to Server.Transfer as it involves a round-trip between the client and the server.
- It does not allow transferring data between pages directly. You need to use query strings, session, or application variables to pass data between pages.
- It can redirect to any URL, not necessarily within the same application.

In summary, Server.Transfer is used for server-side redirection within the same application, while Response.Redirect is used for client-side redirection to any URL.