compatability testing:
                      it is also known as portability 
testing, during this test we will(test enggs) validates 
that whether our application build is running on customer 
expected platforms or not?
     eg:operating sytems,compilers,browsers..etc
there are two types of compaltability problems we hav such 
as forward compatability and backward compatability.
    
Configuration testing/hardware compatability:
                during this test test enggs validates 
whether the application build is suppporting different 
technology hardware devices or not?
      eg diff technologies of printers
          "       "          "  n/ws
          "       "         popology n/ws.......etc

both are the concepts of non-functional testing 
Compatibily is testing is done on platforms,"whether our 
software is running on customer expected platforms or not"?
It is also called as portability testing.That means what 
s/w we develop it should support all other operating 
systems.

Configuration:Here we check whether pur s/w is supporting 
all types of h/w devices.