as per my knowledge i think qtp supports oops based 
applications where as winrunner  doesnt support oops apps.

We can test the applications which are developed using .Net 
using QTP.But we cant test using WINRUNNER

WIN-RUNNER VS QTP :

1.Winrunner doesn't support web applications
  QTP supports all kinds of web application

2.Winrunner only supports IE and Netscape Navigator
  QTP supports all types of browsers

3.The deafult time setting of Winrunner is 10000 ms
  The deafult time setting of QTP is 20000 ms

4.The logical name of true and false in Winrunner is 1 & 0
  The logical name of true and false in QTP is True and 
  False

5.Winrunner doesn't provide the snapshot of output
  QTP provides the snapshot of output.

6.Winrunner doesn't support Uni-code compatability
  QTP supports Uni-code compatability

7.Winrunner has Four kinds of Add-Ins
  QTP have Four kinds of Add-Ins

8.Winrunner has 3 kinds of Checkpoints,2 kinds of 
  Recordings,and 3 kinds of Exception Handling mechanisms.
  QTP has 7 kinds of Checkpoints,3 kinds of 
  Recordings,and 4 kinds of Exception Handling mechanisms.

9.In Winrunner GUI Spy is available
  In QTP Object Spy is available

etc...

sorry i have missed one important one that is

10.Winrunner uses TSL script(Test Script Language)
   QTP uese VB Script.