There's a list of the new stuff in PowerPoint 2002 at
http://www.echosvoice.com/ under Gotcha's, I think. That will tell you a
lot.
Remember, a new Viewer will be release later this year and the problems will
go away. Also, if you open PowerPoint 2002 and go to Tools > Options > Edit
and disable the three items at the bottom, you won't have to worry about the
differences because you won't be allowed to use the new features. It's a
handy setting when designing a presentation that will need to be distributed
with the Viewer. However, turn the features off before you build the
presentation.