Also, with Revolution you need a vet to call in a prescription. With Frontline Plus, you do not. Then you have to dose heartworm preventative separately.
I just found Revolution for puppies and kittens!
http://store.yahoo.com/entirelypets/revforpupand.html
Here is the general page:
http://store.yahoo.com/entirelypets/revhearandfl.html
Frontline plus is on there as well. JUST BE SURE THAT THE COMPANY YOU ARE ORDERING FROM IS IN THE UNITED STATES. I just do not feel safe buying the "same" meds from Australia, which is typically where they are from. If the 6 month supply of either drops much below $45, check where they are located. I know a 6 month supply of Frontline Plus for cats at my mom's vet was close to $80. That's why she had me order online for her.