Steel is made by adding iron to carbon, which hardens the iron. It is also known as plain carbon steel or mild steel, which has higher carbon content with low melting point.

On the other hand, stainless steel has a high chromium content that forms an invisible layer on the surface of the steel to prevent it from staining.

When stainless steel is prepared from steel, chromium, nickel, nitrogen and molybdenum are added.

Carbon Steel 

Carbon steel is composed of iron and 0.12 - 2.00 percent carbon. The broader definition includes alloy steels, which can also contain up to 10.5% alloy content. Even within the confines of under two percentage points of carbon, there is huge variance in physical characteristics—especially hardness.

Stainless Steel 

Stainless steel contains iron, carbon, and at least 10.5% chromium content. The chromium is key—it reacts with oxygen to create a passive layer that protects the steel from corrosion. That protection allows stainless steels to function in wet environments without rusting. The higher the chromium content, the better the corrosion resistance.

Stainless steel is resistant to corrosion and steel is prone to stains and rusting. Stainless steel does not rust or corrode easily.

Stainless steel is used mainly because of its ability to function in wet environments without rusting. 

Therefore, stainless steel is considered better than steel.