The J-10 was based on the cancelled J-9, which was designed over a decade before the Lavi ever flew. Comparing it to the Flanker variants is particularly egregious, too: the J-16 and J-15 have essentially the same overall airframe as their forebears (albeit with significant upgrades), while the J-10 is significantly larger and heavier than the Lavi, has a different canard arrangement, a more powerful engine, a completely different gun setup, different intake geometry, lacks wingtip AAM pylons, etc., etc. Even if they benefitted from IAI's data in some way (and to my knowledge there's no paper trail for that as there is with the J-15, for instance), the sheer scale of the differences make it an entirely new aircraft in a way that the J-15 and J-16 aren't. If it really is a copy, why change so much?
