You have 14 days to use whatever you want. If you do 10 days in the main parks, you can use the additional 4 to go to Waterparks, Disney Quest, etc.
The biggest difference is that unlike Park Hopping with the main 4 parks, each of the various experiences is counted separately. For example, if you go to Typhoon Lagoon in the morning, Blizzard Beach in the afternoon - and decide to play a round of mini golf at Winter Summerland while you're there - and finally, hit Disney Quest in the evening, you will have used 4 of your 10 WPM allotments in a single day.
Also, if you go to Typhoon Lagoon on the same day you go to a park, you will have used both a Park Entrance day and a WPM allotment in the same day.
Hope that all makes sense!
Have a great trip!