Google Play Store is the same @ Android TV and Google TV, but it's auto-filtered to only show apps compatible with your device. Majority of available apps are the same regardless of whether you use Android TV or Google TV, however there are some noteworthy exceptions. Apple TV is availabe on Google TV, but not on Android TV as of yet. Also, some off brands @ Android TV aren't Netflix and/or Prime Video certified.
"Google TV" is just a new launcher on top of the same old Android TV OS, so yes, you'll get the same Play Store as in any other certified Android TV device.