Yes, the two deals are at completely different levels. In fact, you could say they have no relationship whatsoever. Ka-52 is more transactional whereas SSN is much more strategic. The latter would take the relationship to a new level - but then again Russia has been willing to help China in EWS, and both countries claim that their relationship are better than an alliance. It's time to show that. (Btw, Iran is officially admitted into SCO now).
Also, the proposed SSN deal will not come at the expense of whatever PLAN plan to do with its SSN & SSBN fleet. I figure China would need to rival the US in its SSN fleet eventually and it'll take a while for the domestic SSN to scale. There is plenty room for a dozen Russian SSNs if a deal can be struck.
I think "they have no relationship whatsoever" is a very accurate description of comparing this purchase of Ka-52s and a notional move to buy Yasen-Ms (which like you said, is a wholesale strategic level alliance with significant).
Leaving aside every other difficult aspect about the Yasen-Ms (negotiations, infrastructure, combat systems, technology exposure sensitivities), tbh I'm not even sure if the timing of when they could conceivably even arrive would be worthwhile for China.
Considering the pace with which Russia has been producing Yasen-Ms for their own navy, and the relatively large order log they have for those SSNs, but the time their production line is able to deliver submarines to China, I would've expected Bohai to be well underway with production of competitive domestic SSNs with other world leading designs (09V being the one we expect, though they'd be preceded by a run of 09IIIBs).
Also, manning for nuclear submarines is technically finite -- with the PLAN likely to exploit the production potential of the new Bohai facility (20 SSN equivalent slots in the east and south assembly halls!), I have a feeling the trained manpower and the expertise to run those submarines will be consumed quite readily, and adding a dozen Yasen-Ms on top of that, depending on timing, might be a bit much.