No mystery here - through the years vsonic released several versions of the gr07. First there was gr07, then gr07 mk2 (the OGs), then gr07be (bass edition), then gr07c (classic), then gr07x (limited run with new driver and supposedly the best sounding one to date, good luck finding someone outside China who has heard the updated version), then gr07 with detachable cables, then gr07ae (anniversary edition - with the new graphene drivers like gr09), then gr07w (wireless version), then the super duper limited updated version of gr07x. All gr07 versions are plastic - the white gr09 is ceramic.
At the moment the classic and bass edition have newer 2017 ans 2018 versions with upgraded build quality - still plastic, but with better materials. The version with detachable cable is the same as always. The older versions have been discontinued and by the end of the years all gr07 versions should be discontinued to make way for the new models