The difference in scoop count is because of the size of the scoop. S26 scoop holds 2x the amount of NAN.
Our baby used to be on Enfalac A+ since birth but we switched him to S26 after 3 months as we found Enfalac too heaty for him. We first tried NAN but found it did not dissolve well with many particles and also our boy's poo was too watery.
We tried S26 and so far so good after 2 months.
One should not add too much water and dilute the fee unnecessarily. Add'l water should be given separately.