I don't play much games on iOS, so without further information it seems both are directed at pushing friends to install/log into the game. What points fundamentally differ in your opinion ?
one rewards spamming, the other involves a game mechanic where you ask your friend to do something for you(though it's possible to bug your friends that have nothing to do with the game, if you are inconsiderate person). It's O.K. to ask your friends for a help but it's still your duty to think about bothering if your friend would be annoyed or not.
If your friend plays the game - sure. If it's a random person from your friend list who never used the game on the other hand - that's just exploiting social behavior to make money.
