Specialized vs S-Works

There are a lot of car and motorcycle racing fans at Specialized. It was - is - a tradition for US car and motorcycle companies to run a 'Skunk Works' - a development and manufacturing facility off to the side of the mainstream production so that racing specials and one-offs could be worked on without distracting the serious commercial part of the business. S-Works at Specialized serves the same purpose - special products can be worked on, tried and shipped in smaller numbers than usual but with the added marketing twist that by only selling the resultant S-Works products through the best, most enthusiastic and qualified dealers there is a certain added cachet all around. Plus, they can better control which trained mechanics get to tweak the really high-end products for theoretically fussier customers. A concept that's successful in the S-Works line will invariably make into mainstream production eventually. Expect the 2015 Allez to feature Venge-like features, for example, if the Venge continues its good start.

Tarmac, Roubaix etc aren't sub-brands, they are models.

S-Works are the top end Specialized frames/bikes, fairly limited in numbers and only available through Specialized S-Works dealers. Many models have S-Works versions... Tarmac, Roubaix, Shiv, Transition, Ruby, Epic, Enduro, Stumpjumper (both FSR & Hardtail), Enduro...