There are several ticket types.
1. A base ticket. Gets you into any ONE of Disney's four main theme
parks (Magic Kingdom, Animal Kingdom, Epcot, Disney's Hollywood
Studios) per day.
2. A Park Hopper ticket. Allows you to enter more than one of the four
theme parks per day. This is a flat fee for the length of your stay.
3. A Water Park Fun & More add-on. This is another flat fee option
can be added to either a base ticket or a Park Hopper. The WPF&M
option allows you a specific number of admissions to the Disney water
parks or DisneyQuest. The number of WPF&M admissions you receive is
equal to the number of days of theme park ticket you have. For example,
if you have a four-day base ticket and purchase the WPF&M add-on,
you will be given four admissions to the water parks or DisneyQuest.
The cost to add this option is the
same if you have a 1-day theme park ticket or a 10-day theme park
ticket.
Theme park admissions and WPF&M admissions are unrelated. To answer
your specific question, if you have a base ticket with the WPF&M
add-on, you can go to both ONE theme park and a water park or DQ in the
same day. If you have a Park Hopper ticket you could go to two theme
parks in a day, but not to a water park or DisneyQuest. If you have the
Park Hopper with the WPF&M add-on, you can go to more than one
theme park AND a water park or DQ.
You can find related questions
HERE,
HERE, and
HERE.