sulphate Nickel vs. Sulfamate Nickel

A. As a general rule, sulfamate nickel is used for engineering purposes and electroforming while sulphate nickel is used for decorative brightwork.

Again, it's a general rule, and many shops will have only a single solution for both types of work. But the sulfamate nickel is generally an easier match if the component will be deformed or soldered and the sulphate nickel an easier match for brightest appearance.

A. As Ted says, sulphate nickel is mainly decorative and sulphamate is engineering nickel. However, before nickel sulphamate was available the only engineering nickels were chloride or sulphate based. Sulphamate can deposit much lower stressed nickel than all the others and has the advantage it does not necessarily need additives, although in reality, to get neutral or compressive nickel, you do need some. It happily works at lower temperatures and also doesn't need chloride in the electrolyte if you use sulfur nickel anodes. I am not aware of any corrosion properties, although I believe there are claims that sulphamate produces a slightly harder deposit. I cannot, however, verify this.