The conversion between Word 6 and Word 97 involved the change from WordBasic
to VBA. There's no such conversion between Word 2002 and Word 2007, as they
both use the same VBA.

There are some new objects and methods in Word 2007, of course, and if you
use them in macros you write in Word 2007 and try to run the macros in Word
2002 then you will get compilation errors. The easiest solution is not to
use any of the new objects. Fortunately, a new feature of the VBA help in
2007 is a notice at the top of a help topic if it describes something new.
If you can't or won't avoid new things, you'll have to segregate them into
modules that get loaded only if the current Word instance is 2007.

There are also some things in Word 2002 that will no longer work, or at
least work correctly, in Word 2007. The main things to look out for are
custom toolbars and menus (CommandBar objects and their descendants) and
AutoTextEntries, and some of the Options members.