Difference between Su-35S And Su-35BM?

How are they different? And, what exactly is the Su-35BM?

The Sukhoi variant designations can be confusing, but it appears that the 35S is the current VKS line version of the aircraft with the N035 Irbis-E radar, whereas the -35BM appears to be a Sukhoi prototype or development aircraft for future / continuing modernisation of the Su-35 platform. Not sure what new stuff the -35BM features but it appears that one significant upgrade is the ability to carry the R-100 very long range AAM.

I wonder what the point of the -35BM is given that the Su-57 appears to be nearing serial production, but given the announcement by Russian defence minister Shoigu that the Su-57 would only enter low rate production for now, maybe it still makes sense. Even more so given that Sukhoi is looking for export customers for advanced Flanker variants. I doubt anyone will be offered the Su-57 for a number of years.

The Su-57 is probably dead in the water at this point. There will probably never be more than a handful of them built. Makes more sense to invest in "near equal" aircraft and fine tuning existing designs due to economic reasons.

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Clarification : Unless you plan on fighting a major world power you really don't need super expensive stealth tech. As it's doubtful Russia could defeat either of their immediate rivals in anything other than a purely defensive war.... there's just better places to spend their limited funds.

The Su-57 is probably dead in the water at this point. There will probably never be more than a handful of them built. Makes more sense to invest in "near equal" aircraft and fine tuning existing designs due to economic reasons.

 

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Clarification : Unless you plan on fighting a major world power you really don't need super expensive stealth tech. As it's doubtful Russia could defeat either of their immediate rivals in anything other than a purely defensive war.... there's just better places to spend their limited funds.

Agreed. Since the F-22 program only produced a (relatively speaking) small number of airframes, it makes much more sense for the Russian ministry of defence to allocate scarce funds to procuring advanced Flanker versions like the Su-35S to replace the ageing Su-27S fleet than it does to allocate the same funds to producing something that won't produce any cash from exports and would be very expensive to produce in any numbers. It wouldn't surprise me at all if the Russian VKS continues to use advanced Flanker versions out to 2025-2030 and maybe even beyond that, with a couple of squadrons of Su-57's for 'just in case' scenarios.