It's true that LFR, normal and WOW Classic TBC Gold heroic are all the same set , with color changes but it's the mythic set (and certain pieces) which is different.
Reskin skin employs the same skeleton however it layers on a different layer. If the skin changes aren't excessively severe, they could be identical to Recolors. They may also add additional bits and bobs.
The Iron Skyreaver is an rylak mount skeleton. It has very loud jet thrusters on its wings and armor. This is an update to the skeleton.
Recolor is the name given to the difference between the Black Drake mount (10 Sarth) or the Bronze Drake mount (10 CoS). The model and buy WOW TBC Gold the skin are the same, except for the color. Experiment 12B is a color change of the drake mount's basic color.