OMFG.....this is actually Lockdown's master plan in the ROTDS game:
to restart the war by bringing Decepticons from the past into the present all so he can MAKE A PROFIT and get business booming again.
As for whether it's two different universes or just the past/present......it's two universes and that is only confirmed by a pre-credits scene showing G1 Optimus. But we barely got anything explained.
BTW as for when the Fall/War for Cybertron series falls.....seperate from the movies and it's part of the aligned/Prime continuity. There's a scene where Shockwave's going through datalogs and we hear history such as the Patterners, Jhiaxus and Galvatron along with the 13 original Primes. Everything is found in this massive overpriced book whyose summry you can read here:http://tfwiki.net/wiki/Transformers:_Th ... _of_Primus