I am sorry, but I do not understand what "certified for EN for europe means".....
It is european committee standard for using the regulator in europe
how does the new model differ from the older model on sale for $274.95? is it purely cosmetic or is their a functional difference?
It is a completely new design of both the first and second stages. Mostly it is cosmetic, the first stage is still a balanced design offering excellent performance, but also a new cosmetic design.
Is this functionally identical to the regular Oasis without the Red cover?
Yes, its just a newer model with cosmetic differences.