Stainless steel is relatively wear-resistant, and stainless iron contains little Ni. Its high-temperature performance is poor. Its grains are not as fine as stainless steel, and it is also easy to rust.
We usually think that stainless iron is 1Cr17 (ferrite) series, 1Cr13 (martensite) series, and other materials containing only Cr but not Ni. Stainless steel is only stainless steel containing Ni and Cr. Generally speaking, stainless iron is easy to damage and less wear-resistant after heat treatment and hardening, while stainless steel has too strong ductility, resulting in fine chips during friction and better wear resistance.