I confirm, the Nismo filter has around half the number of pleats compared to stock, and surface area is indeed less than stock. However, the material's type and its density would also affect the filtering as the filtering is not only on the surface. Both filters seem to have the same depth.

Anyway, since Nismo S-tune parts do not violate the warranty, I believe the filtering must be within the acceptable range, and I can feel the improvement in performance (very good but-dyno).