What is the difference between traditional Mexican cooking and Tex-Mex? Most Americans (including myself) have grown up on Tex-Mex thinking it was traditional Mexican cooking. I was able to eat traditional Mexican (I thought) at a small cafe in downtown Denver. It was delicious and savory. 

My question is what is traditional and what is Tex-Mex? What spices are used, etc? 

I see sour cream, cheese, etc., in Tex-Mex but the traditional was a taco platter, stewed meat or meat in a sauce, a bit of garnish but absolutely delicious! Simple but great flavor. Thanks! 

(To clarify my statement to avoid confusion, I like Tex-Mex but the "traditional" Mexican I believe I experienced was delicious, simple and different. I was seeking spices used to differentiate, ingredients used in traditional and not used, and example dishes)
I'm not an expert by any means, but here's my understanding of the situation:


There are many different regional cooking styles in Mexico, not all similar to the northern Mexican food upon which Tex-Mex is based.
Overall, relative to Tex-Mex cooking, there tends to be less focus on heat, cheese, and beef.
Cheddar cheese is a more recent addition in some northern Mexican cuisines (eg, Sonoran).
Although wheat is used (for rolls, empenadas, etc.), flour tortillas are typically only in northern Mexican cuisine.


Common "Mexican" dishes that were created in the United States : fajitas (Tex-Mex, inspired by arracheras), mission-style burritos (San Francisco), chimichangas (Arizona).