> 1)What is the difference  between
> <@ include> & <%jsp:include%>

<@ include> Includes the file at translation (compilation) time,
inserting it into the file as it is built. It becomes part of the
servlet code.

<jsp:include> Includes the OUTPUT of the included file at request
time, and so amounts to being some inserted HTML code.

> 2)In two ways we can crete thread
> 1.Runnable interface
> 2.Thread class
> which one is better & WHY ?

Don't know.
> 3)what is the difference between GEnericservlet &
> HttpServlet ?

HttpServlet is a subclass of GenericServlet and adds the doPost and
doGet methods to handle http requests.