The seams and the colors both. I have had enough of these big Akros in hand to know one when I see one.
The lower left is a newer MK imho. MK made a lot of "Rainbows"--- the later they are, the less bands that they have. Many here can push it into a more subjective conclusion.
The Vitro is just a gut thing—when in doubt ---go with your gut.
Marble—On!!