To me, it's easy - Salt System if what you mean is Salt Water Chlorine Generator (SWCG).

The Pool Forum promotes simple, safe, and inexpensive chlorine sanitized pool care using readily available chemicals. Chlorine is one pool chemical that is consumed (most are conserved) and must be replenished. SWCG is one way to replenish chlorine that many find convienient - it seems to be similar in total cost to other chlorination methods.

I don't know what new Fusion Nature Two is but I suspect that it won't really be cheaper and such claims won't survive close examination. It is especially problematic is the system uses unknown or trade secret formulation or mineral (metal) as metals cause pool water problems and so do secret ingredients.

Unsolicited advice:
The most important start-up chemical is a Taylor K-2006 test kit. Next is probably water.