One thing you may have noticed about the Nexus 7 is its home screen looks eerily similar to a blown up version the screen you’d see on the Galaxy Nexus running Android 4.1. The simple answer to that question is yes, that’s exactly what it is. There are hints of a tablet UI when you enter apps but the main screen doesn’t look that different than a smaller t=device.
The reason being is that Android 4.1 will look different depending on the screen size of the device. Everything depends on the screen density and if you’re device has a larger display, your UI will look more like the traditional tablet UI for Android. This was done to help developers unify their apps so there doesn’t have to be a different app for different type of Android devices. In short, all Android apps if developed right will be both a phone and tablet app. Check out an explanation about this directly from an Android developer below.
As Android engineer Dianne Hackborn explains it:
For developers, when designing your app to scale up from its phone UI, this mostly means you should pick the break point at which any major change in your layout should occur and let the layout managers take care of all of the sizes in-between. …
Android’s density scaling was designed to be able to support arbitrary densities, by including the concept of density in all of the UI specifications of the application (bitmaps, measurements, etc) and using layout managers for final pixel-accurate placement of UI elements. …
You don’t need to supply bitmaps for every possible density; Android will scale your bitmaps (typically when they are loaded) to match the current density.