The first 2 are Feliway. The second is a product by Farnam that contracted w/ Feliway to add Feliway to its products. It's possible that Farnam purchased Feliway . . . but I do know that you can get BOTH Feliway and Comfort Zone (with Feliway) now. I'm guessing that straight Feliway is a higher concentration, but the last time I got it, when Jonah arrived unexpectedly, I got the Comfort Zone b/c it was what PetStupid had, and it seemed to work fine.