Erm, yeah, thanks, but I already knew all of that.
But the reason I asked that is, of course, because the Marian reforms are really the most drastic change. It introduced standardized, state-supplied kit; made pretty much all infantry into principes, as opposed to the graded troops the likes we see in New Vegas; and stabilized the unit-strength into the non-indicative numbers we all know and love today (i.e. 80-man Centuriae). It's really the biggest turning point in Roman military history, that that turned what was really a conscripted militia of bumble[censored] farmers, who lost pitifully to Brennus and had to hide from Hannibal, into the professional military machine that would enforce the claim of MARE NOSTRUM over the entirety of the Mediterranean.
To insist that any of the subsequent change is comparable in impact is just being didactic to the point of error.
Rome exists to archaeologists who've brushed Nero in his hundred-fold aspects, armchair historians, those who play general, and textbooks. Each is a different city; one is streets in exerted detail, but another is stoned spectacle. One is historic and another superficial. But where Rome is withdrawing into imagery, Cyrodiil is gradually actualized; she's becoming real. So, the difference is Rome's legions are a fiction.
Are you available for birthday parties?