What is the difference between the sims 2 and the sims 2 pets for the psp?

i knw tht in the sims 2 pets you get to hve pets.|||I believe that you need to get the sims 2 first. Then get the Sims 2 pets as an expansion pack. You need to have the sims 2 in order to be able to use the sims 2 pets, i think.|||You kind of answered your own question. The major difference is one gives you pets, one doesn't. Also, there are more deorating options with the pets and more items.