The Nelsen SP3 Scale Prevention System will remove sediment, chlorine and chemicals, and will condition the water hardness so that it no longer forms scale or bonds with glass or metal. It does not remove calcium or fluoride from the water. The Home Master Softener will remove calcium from the water and put salt in its place.
Both systems are effective at treating hard water problems but produce different feeling water. The Nelsen SP3 water feels like natural spring water, whereas the Home Master Softener water feels either silky or slippery depending on you. Some people will use both -- the Nelsen SP3 system on their main water so that all water is treated, and the Home Master Softener just before the hot water heater so just the hot water is salt softened.
The Nelsen SP3 system will also remove all the chlorine and chemicals from the entire water supply and requires annual maintenance of its Home Master Filter. The Home Master softener will require that you fill the salt bucket regularly, and can be combined with the Home Master Filter if you want whole house filtration. Please note that you will need to use the Home Master reverse osmosis system in order to remove the salt from your drinking water.