the intention of asking of the question was what is different in it ? why it is separetely required ?
JUnit limits its scope to testing the functionality of a given "unit" of code. With it you can verify that your class works as expected.
JUnitPerf allows you to test the performance characteristics of your code. It extends JUnit's capabilities so that you can verify that, say, a given unit method will always take less than .25 s to run. It's test decorators are also useful for stress testing a given "unit". I once used it to verify the response times of a class which I used as an interface to a remote server. I verified that even with 10 simultaneous users, the response times never grew above a certain level.
Does this answer your question?
Cheers,
Nicholas Lesiecki
Principal Software Engineer<br />eBlox, Inc.<br />(520) 615-9345 x104<br />Check out my new book!:<br /><a href="http://www.amazon.com/exec/obidos/ASIN/047120708X/" target="_blank" rel="nofollow"><br />Java Tools for Extreme Programming: Mastering Open Source Tools, including Ant, JUnit, and Cactus<br /></a><br /><a href="http://www.rickhightower.com/JavaXPToolkit/" target="_blank" rel="nofollow">More Info</a><br /> <br /><br />Check out my article on <a href="http://www-106.ibm.com/developerworks/java/?loc=dwmain" target="_blank" rel="nofollow">AspectJ.</a>