Hi....

Functionality Testing(FT): Here one will check for the 
functionality of an appln.Here the appln should have all 
the fns mentioned by the client and it should work 
according to the client's request.Automation of these 
applns can be done using Winrunner,QTP,Etc.

Performance Testing(PT):Here one checks the performance of 
an appln using various 
paramaetrs.LOAD,STRESS,VOLUME,SCALABITY,SOAK are the few 
very imp paramaters.breakpoints are found out here.PT in 
itself is a big tpoic.if anyone wants we will discuss it 
later.PT id done using Loadrunner.

testing conducted on application w.r.t the client's 
requirements to check for its behavioural, calculations, 
back-end, service order, input domain coverage etc .

Functionality Testing is testing the application to 
determine whether the AUT is perfoming as per the 
Functional design Specification.
                    OR
Functionality testing is testing the AUT to  check the 
descripencies between Functional design specification and 
the  actual results.

Performance testing is testing the AUT to determine whether 
the AUT is perfoming the load and volume constraints as 
specied in SRS and determining the load conditon at which 
the AUT can fail when it is handling high volume of data .

In these functionality testing some functionality like 
these.

If u click on minimized button it will be minimized.
If u click on submit button it will be go to the next page.

Performance testing is nothing but accuracy of the 
application or response of the application. for example the 
application is should be executed within 2 minutes as per 
the srs so we have to test the application how much time is 
taken by giving the response if it is more then expected it 
is a bad performance. So we have to find out which area it 
is missing