Before you start comparing J-11B to Su-30MK, know there are significant differences between their intended functions. Su-30MK was imported from Russia for the Chinese navy, not air force, as a maritime strike platform along with JH-7A. It is a tandem seat fighter-bomber with the primary role of engaging surface targets. J-11B on the other hand, is a single seat A/C designed for air superiority. It serves with the air force, NOT navy. With this in mind, here are the differences:
- Su-30MK has a strengthened frame to carry extra air-to-ground payload compared to J-11B, making it a bit heavier.
- J-11B uses WS-10A engines, while Su-30MK uses Russian AL-31F engines
- A holographic HUD and 3 MFDs were installed on the J-11B as upgrade.
- New radar was installed on the J-11B, with plans to install AESA later on.
- J-11B is able to use PL-12 (SD-10) and PL-9, where Su-30MK requires imported R-77 and R-73.
I'm not going to make a comparison with Su-30MKI since it will only turn into a pissing contest.