Souvenir Cups vs "regular" cups

[OffToDWD]

I've seen conflicting info on Souvenir cups vs "regular" cups. Some say that souvenir cups are bigger than the "regular" cups so purchasing it the first day of cruise may be worth it if we use the souvenir cup when we order drinks during the rest of the cruise. Some say it's the same size (just looks different). Does anyone have any insight on this? And can we get non-alcoholic drinks in the souvenir cups? Thanks!