This may be a silly question, but is the Wii Fit and the Wii Fit Plus similar?

Wii Fit Plus is just an enhanced version of the Wii Fit. Taken from Wikipedia

"New features include a calorie burning counter, the ability for users to create custom fitness regimens or choose from a number of specialized routines based on specific objectives and available time, as well as having the option to create profiles for pets and babies. Users are also able to navigate more quickly between exercises."

It also has 15 new balance and aerobics games. The board is still the same though, it's just an additional disc i guess you could say.