Remenber it is we on the internet who call these planes J-10 A, B or C, those are not official designations. What ever these planes are called I believe that the 201 is an improved version of the J-10B probably benefitting from trickle down technology from the J-20 program.
Yo, ... YES and No. Át least the A, S, AS, H, SH, AY and SY ... and I'm sure the B too are "official" PLAAF designations in the same way the J-7II, III, (aka C), E, G, and so on are official.
However - and that's my point - I actually doubt that there is an official C-designation exactly due to the following argument:
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201 indicate the first plane of the second batch. The extra antenna underneath shows changes to the electronic and avionic suite. The first batch already has 27 planes at the least and we don't know how much more is to come. So if they would start producing the new J-10 version somewhere next year it will be already 2 years between the production of the 2 different models. Not at all too long to make new improvements especially if they can borrow a little bit here and there from the J-20 program. Or maybe the upgrades are not that drastic that it merrits a new designation of its own and we are just getting ahead of ourselfs here.
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YES, it is a second batch production aircraft with "minor" - at least external - changes, which may the mentioned changes that are typical for a second block, but surely not for a new letter. Remember the slightly different changes gradually introduced into the J-10A model from Block 4 on. As such I think it is indeed a bird either already from the second production block, maybe from a second manufacturing line ... and after delivery of these 1-xx-serials we will surely see more with 2-xx numbers followed by 3-xx serials. ... at least I hope so.
Deino