They are different, the difference between a good understanding of the key is a "base" base mean "foundation", popular nickel-based alloys to understand is the nickel-based alloys, nickel accounted for the highest percentage, usually more than 50%, such as Monel, Hastelloy B, C series, and stainless steel for a "steel", a result which accounted for the highest percentage of iron. E.g., 304L, which accounted for 9% of nickel, but the iron content of more than 70%, so it is a stainless steel.