EXPs, SLEs, "B"s, and "B" pros are all 1.5s. In fact all the frames will freely interchange between all those sails.
The difference you feel, is the vertical channeling incorporated in both designs. The "B" introduced this, the pros carried it further. Part of why the pro flies so much better, is that Bazzer (the maker) takes the time to orient the fabrics to get the best stretch from the entire sail. His attention to detail sets his work apart.
The NYM uses some of the ideas from the "B" series - vertical layout and progressive venting, along with the folded LE pocket found on the pros. Only flown one for a short time, not long enough to make a fair comparison.
PS: it is rumored that Bazzer sprinkles a bit of fairy dust on every Pro made!