I have eaten Mexican food in both Cal and Texas. They are different. You cannot seem to get good Tex-Mex in California (Bay area or LA), but you can get good real Mexican food.
Texas has a mix of both, depending on the part of Texas.
Like Italian food. There is good American Italian food, then ther is good Italian food. New York has the best of both. You can get home made Italian in Little Italy, if you want it or you can get the best American Italian food as well.