The products are marketed very differently and have different features. Google Wallet is explicitly hoping to replace your wallet, focusing on loyalty cards, NFC payment, online shopping, and fraud monitoring, in addition to simply sending money to friends.

On the other hand, Square is positioning Cash as a dead-simple way to send money to friends, whether or not they've download the Latest Social Micro-payments App™. Its plumbing. Long run, they are obviously gunning for cards-on-file to support their merchant tools, where they make money hand-over-fist.

Who knows...Square Cash might expand into something that resembles what Google Wallet is today. They seem to be starting with the basics.

Besides that, Google Wallet is available in all 50 states, while Square does not allows residents of Hawaii and Tennessee to send money (only receive it).