In the older vintage Tudors, they were really a Rolex twin with most everything being the same except the movement & dial. Tudor used an ETA movement instead of the Rolex in-house.
Now, they're pretty much completely separate processes. In fact, I don't think they share much in common parts - if any, save maybe the crystal & cyclops. I do not believe Tudor uses 904L but instead uses 316L. I believe for the past few years, they've been separate styles, parts & designs.
As far as servicing, Rolex centers can service & supply parts for Tudor.
Though Tudor still enjoys a rich history, and are a sturdy, well built watch.
First, the major difference: Rolex uses an in-house Rolex movement. Tudor uses an ETA-based movement, that, depending on who you listen to, is either highly modified, tweaked a bit or not at all. (However, there are some very early Tudors that use a real Rolex movement. And the Rolex Daytona used an ETA/Valjoux movement - as I understand it - just like the Tudor Chronograph)
While certain models of Rolex and Tudor share the same cases in vintage pieces, there are differences. My Tudor Submariners have a double lock crown, which according to JBHIII, is different from the Rolex triple lock crown.
On new Tudors, I believe no case parts are shared.
Rolex are generally - if not all - COSC certified for accuracy. Tudor is not.
Hope this helps.
I'm not exactly Mr. Rolex - and while I own four vintage Tudors info on the brand is hard to come by.
LMAO, guess scott and I were responding at the same time.
As the owner of a Tudor Tiger (circa 1997) and a Submariner all I can say is the Tudor fit and finish is on a par with the Rolex, the VJ 7750 whether modified or not runs well within COSC, and it does have the triplock crown.
See my avatar.