The two are actually the same application currently, but Mist is under heavy development. You can run the Ethereum Wallet in Mist mode, just start the Wallet binary with `--mode mist`.

You can find the latest version [here](https://github.com/ethereum/mist/releases).

For example on Mac, run `/Applications/Ethereum-Wallet.app/Contents/MacOS/Electron --mode mist` in Terminal.