NAD+ is for improvement in executive function (cognition, memory) while NMN works synergistically at the cellular level to increase sirtuin activity, optimize mitochondrial function, and restore levels of NAD+ as they were in youth.
That is to say, NMN actively works in conjunction with the body's natural longevity systems.
Although they have similar effects in some organs, there may be differences in the effect they have in other tissues throughout the body.
If we were able to specifically recommend one over the other we would stop offering the obsolete supplement, but as NMN and NAD+ have different effects we cannot categorically say one is better - apples to oranges.
Should future research definitively allow us to recommend one over the other, we will most certainly do so.