@Martian2
Just a small call, mate!
[ … that considering some tensions on fora and specifically between some nationalities, I feel obligated to mention is not an ad patriam attack at all. ]
That composite image with the dual and expanded views of the tail surface is most likely a non-issue.
It does not
conclusively show differences in shape between the two images.
If we start with the AC at level and rate that 0 degrees, then tilt it to the left to get the first view it reaches somewhere in the vicinity of 65+ degrees. The one at top right has passed 105 degrees, probably 110+. ( The directional line of progression is also different from one to the other. )
The tail surface we are looking at is made of two plane parts ( both meanings of plane incl. geometry one ). The stabilizer add-on is seen almost face on and the main fuselage extension encircled is a complex trapezoidal shape to boot tapering from a thick facet inside to sharp edge outboard. By comparison, in the above right image, the stabilizer is reduced to a sliver due tot the different angle and the piece seen protruding below the red circle is now the J_20's portside vertical fin.
To show how perspective influences resulting views, ( which I surmise you know but not clearly whomever made that )
just check how this surface seems close to the port/encircled engine and how big a gap shows on the top/starboard engine on the same leftmost pic, which we then find reproduced the other way around on the second image ( the same gap is seen in circle but would not appear if we had a view of the other side that is cut by top picture border ).
The exact same considerations apply to the rear angle the poster interpreted as being differently shaped. Knowing the implications of the above explanations and again specifying that the two images have the planes shown facing in different directions ( top is coming towards our right as observers while left/bottom is moving straight tight if not somewhat away ), I am far from convinced to say the least that the discrepancy even exists.
To verify this doubt, just compare the original uncut view of #215 ( your top most image ) to the one of #213 ( your bottom most one ) which have less of a tilt spread between their PoV angles and you'll find the mirrored angles of that edge to be pretty darn similar.
One could finally add that the shaded areas in the composite are a manipulation : the cut of leftmost being made to fit the wing sweep; the canard and wing of top right extending into the close-up & an unexplained shadow protruding over the wing that does not fit any part of the plane in the close-up as if a botched attempt to show the vertical fin extending but spaced leftward inexplicably.
My conclusion is that the composite image is at best meaningless and at worst made-up, i.e. a lie.
I, for one, am NOT saying this is means anything regarding the program or the number of J-20 produced/flying. It only raises serious questions as to either the understanding or integrity of the person that manipulated these images and does not in any way detracts from the program's worth or China's honesty …
but its value as an informative piece is non-existent.
Thank you BTW for your statement on the decimal meaning to which I agree entirely, the 01-02 being testbeds for the aerodynamic formula and flight qualities of the platform without much or any military electronics and the ones past the ten mark those fitted with war systems, something that I had arrived at on my own ( A.K.A development program jump/increment ).
Ni Hao, Tay.