It is right, in all aspects, the vex all serve under one mind, and as far as vanilla players new this is the beast we killed long ago, Atheon, Times conflux, since then we have found out that the vex all come from different strands e.g the sol progeny, axis invasive. This along with the vex line mentioned in a vex story mission "the vex all work from one mind" they have the tactical ability to change the strategy due to what has happened to one of its soldiers, if something happens to one, all know, the cabal however are slow creatures, they walk about and use jump packs to compensate for their heavy sluggidh bodies, and use heavy rifles and high-calibur weapons to kill the things they cant see, this slowness also accounts for the fact it would take them a while to get to earth, the emperor or whatever they call it in cabal language, whilst the vex have teleportation powers and many like the minotaurs, as said in the background info on its grimoire card "uses its teleportation aggresively" we know that all vex can teleport, and since all ultras are enlarged versions of the miniature ground units e.g a gatekeeper, another name for one of atheons high ranked hydras can teleport, vex goblins can, harpies can, but tend to not as it doesn't fit their attack style, and also the harpy unit has to wait a short time before being able to attack, leaving them behind in fast paced battle, that is why i believe it is right