The Galactic Empire consists of two general regions; first, the inner worlds, which are considered the important part. The outer rim, a broad area, includes various low-value balls of rock like Tattooine, which the Empire could hardly care less about - some script editions and the novels have Luke's friends on Tattooine guessing it would be unlikely the Empire would even fight to keep a system like Tattooine. 

In general, the Rebels are funded, organized, and draw most of their strength from the inner worlds, but mostly operate within the outer rim to avoid detection.

The Empire has been "imperializing" private property, in a curious echo of cold war rhetoric; at the same time, Imperial stormtroopers are described as "facist." It is unclear precisely what political ideology the Empire follows, but it is clearly intended to be unpalatable to the audience.