These are the new features which are available in QTP8.2 and which are not present in 6.5 version.

Keyword View: Lets you easily build and maintain tests without writing
VBScripts.

Auto-Documentation: Provides improved test clarity and the ability to
view test steps in plain English.

Step Generator: Allows you to quickly insert custom-built functions
into your tests.
Mercury Business Process Testing: Enhanced integration with BPT --
Business Components, Scripted Components, and Application Areas.

Enhanced Expert View: Provides greater efficiency when generalizing
test components.
Action Parameters: Allows you to generalize testing actions for greater
reusability.

Data Parameters: You can now specify test or action parameters to pass
values into and from your test, and between actions in your test.

Open XML Report Format for Test Results: Test results are now stored in
an open XML format, enabling you to easily customize the reports
according to your own requirements, and to integrate the test result
information with other applications.

Unicode Support: Lets you test global deployments of your enterprise
applications.

Function Definition Generator: You can use the new Function Definition
Generator to generate definitions for user-defined functions, add
header information to them, and register functions to a test object.


http://www.mercury.com/us/products/quality-center/functional-testing/quicktest-professional/