The fronts are pretty basically identical. The colors vary just a tad. But color variations were found even within cards from the US set. I'd say it would be darn near impossible to tell which of the three you've got just by the front.
Turn the card over and it becomes a little more distinguishable. The OPC card is a much lighter shade of orange while the Venezuelan card has a darker tint. Of course the line on the very bottom of the card also tells you exactly which you've got.
I'm happy to have all three.