Google VR is Google's own VR software and it's basic. Vlingo is a third party app that somehow got in good with Samsung that's more intuitive.
Vlingo does more such as read text messages and email natively. Pico TTS needs other 3rd party software to read text and email. If you use Vlingo, use samsung TTS (text to speech) as it sounds better and gives you options on how it sounds. If you you use pico TTS, your stuck with one sound only (sounds like the original TTS found on the EVO, EVO 3D, etc.). If you pair Vlingo with svox TTS (in the app market free or paid), you can download voices ( not free ) for custom personalization.
I personally like and use Vlingo with svox TTS (grace voice) (in driving mode when paired with bluetooth) for a total hands free experience when driving.