The key ingredient of Su-33 is the carrier-ready modification to the basic Su-27 design, borne from the same root means they got to look alike, and being the first generation design attempt the interior would be very similar too, that's unavoidable. The prototype China obtained from Ukraine gives hint to what the Russian obviously won't want China to learn...well, eventually China might crack the secret to carrier-borne aircrafts, but it'd take a long time if without outside help.
Clearly though, China's can get a upper hand in terms of avionics and even some adoption of composite materials - Russia's only got the budget to revamp its arsenals in the recent years. But overall China is still behind Russia, especially when comes to engines - China still can't produce good aircraft engines on par with the Russians', which in respect inferior than the western blocs' that leads the world.