http://www.renfe.es/ave/ not sure if you speak spanish.

3 classes are Club, Preferente y Turista.
Tourist is the basic, 4 to a row and the bulk of cars.
there are usually 2 cars of Preferente which is first class with meals. The Club levels gives you drinks in your seat, a less crowded car but the same seat as Preferente and a la carte meals. Probably more exclusive.
When I took the AVE from Madrid to Sevilla and back there was no Club class and Preferente was very nice. The equivalent of the First Class Thalys (Amsterdam-Brussels).
I think the trend in rail service is to give people that third level which usually you cannot access with Railpasses, therefore most tourists stay away from it and it usually carries a 30% price premium over first class.