Difference between QTP8.2 and QTP9.0/QTP9.2

Over and above features provided with QTP 9.0 , QTP 9.2 provides following features:

Mercury Screen Recorder :
Capture your entire run session in a movie clip or capture only the segments with errors, and then view your movie from the Test Results window.
Dynamic Management of Object Repositories:
QuickTest now has a new RepositoriesCollection reserved object that you can use to programmatically manage the set of object repositories that are associated with an action during a run session.

Over and above features provided with QTP 8.2 , QTP 9.0 provides following features:

Object Repository Manager:
You can use the Object Repository Manager to manage all of the shared object repositories in your organization from one, central location. This includes adding and defining objects, modifying objects and their descriptions, parameterizing test object property values, maintaining and organizing repositories, and importing and exporting repositories in XML format.
You can open multiple object repositories at the same time. Each object repository opens in its own resizable document window. This enables you to compare the content of the repositories, to copy or move objects from one object repository to another, and so forth.
Object Repository Merge Tool:
You can use the Object Repository Merge Tool to merge the objects from two shared object repositories into a single shared object repository. You can also use the Object Repository Merge Tool to merge objects from the local object repository of one or more actions or components into a shared object repository.

When you merge objects from two source object repositories, the content is copied to a new, target object repository, ensuring that the information in the source repositories remains unchanged.

If any conflicts occur during the merge, for example, if two objects have the same name and test object class, but different test object descriptions, the relevant objects are highlighted in the source repositories, and the Resolution Options pane details the conflict and possible resolutions.
Multiple Object Repositories per Action or Component:
QuickTest provides several options for storing and accessing test objects. You can store the test objects for each action or component in its corresponding local object repository, which is unique for each action and component. You can also store test objects in one or more shared object repositories that can be used in multiple actions and components. Alternatively, you can use a combination of objects from the local object repository and one or more shared object repositories. You choose the combination that matches your testing needs.
XML Object Repository Format:

QuickTest now enables you to import and export object repositories from and to XML format. This enables you to modify object repositories using the XML editor of your choice and then import them back into QuickTest. You can import and export files either from and to the file system or a Quality Center project (if QuickTest is connected to Quality Center).
Function Library Editor:

QuickTest now has a built-in function library editor, which enables you to create and edit function libraries containing VBScript functions, subroutines, modules, and so forth, and then call their functions from your test or component.
Handling Missing Actions and Resources:
Whenever a testing document (test, component, or application area) contains a resource that cannot be found, QuickTest opens the Missing Resources pane and lists the missing resource(s). For example, a test may contain an action or a call to an action that cannot be found; a testing document may use a shared object repository that cannot be found; or a testing document may use a object repository parameter that does not have a default value. In all of these cases, QuickTest indicates this in the Missing Resources pane, enabling you to map a missing resource to an existing one, or remove it from the testing document, as required.
Source: What's New in Quick Test Professional--QTP Documentation