The only app stores exclusively for tablets are the Kindle Store and Nook Store, as of 2015. Ipads get apps from the iTunes Store, while Android tablets access apps in the Google Play store. Both of these also supply apps to all other Apple devices and Android phones.
The Nook Store at BarnesAndNoble.com only supplies apps for Nook tablets. Other stores provide apps for multiple devices.
Most iTunes apps are available on all Apple devices, including iPad tablets and iPhones. Google Play provides apps for a variety of devices that operate on the Android OS, such as the HP TouchPad and all Samsung Galaxy devices.