The difference between Su-30SM and Su-30M2 is quite huge. Starting from engines ending with avionics. Su-30SM is more advancer and more functional then Su-30M2. They even visually looks different. They also made by different factories.
Su-30M2 uses here mostly as combat-training jet for pilots of Su-27SM and Su-35.
Su-35 - is a single set fighter jet which is close to 5th generation then to 4th generation.
Lots of composite materials in airframe, modern avionics, more powerful radar and engines and so on.
