Side note: I didn't really like how this match ended as I thought Aoki was screwed due to his legs hanging off the stage (potentially pretty dangerous too due to the extra leverage).
The reason for the difference - in my mind - is that in the Gi one of Kron's favourite submissions is the loop choke. I think this because of how he sets it up from 11:44 onwards (just as you would a traditional loop choke). The loop choke forces you to close your fist because you are gripping the gi. This 'giotine' is him bringing over his set up and traits of the loop choke into NoGi. Essentially it is a loop choke that is secured with the free hand as opposed to secured with a grip on the gi. The choking hand cups the chin as a substitute too I guess.
Marcelo's giotine is as much about the fact he attacks just the neck as it is the grip, I believe. The elbow allows extra leverage and for you to hide your wrist from your opponent. Kron's giotine at the point you refer to is an arm in and there is always a possibility of defending in that case (the finish is too).
Notice Kron's failed attempts - Marcelo, once it is locked on, is pretty much finishing you.