It's closer to the sun in the morning!

But seriously, different in what way? There are many many possible answers to that question.

Landforms? Geology? History? People's attitudes? Foods? Industries? Indian tribes? Home styles? Clothing styles? Cultures? Flora? Fauna? Transportation?

What are the four regions?

Have you done any web searching?
I found this site:
Texas — History.com Articles, Video, Pictures and Facts (http://www.history.com/topics/texas)