Carbon steel and stainless steel are both metals that are used in a wide array of commercial and consumer applications. The main difference between the two is in the components that are added to the steel to make it useful for its intended purposes. Carbon steel has a higher carbon content, which gives the steel a lower melting point, more malleability and durability, and better heat distribution. Stainless steel has a high chromium content that forms an invisible layer on the steel to prevent corrosion and staining.
To the casual observer, carbon steel and stainless steel are easy to distinguish. Carbon steel is dull, with a matte finish that is comparable to a cast iron pot or wrought iron fencing. Stainless steel is lustrous and comes in various grades that can increase the chromium in the alloy until the steel finish is as reflective as a mirror. The coating provided by the chromium makes stainless steel attractive in its natural state, without needing to be painted or otherwise finished.
Functionally, stainless steel is preferred for many consumer products and can be used decoratively in construction, while carbon steel is often preferred in manufacturing, production and in projects where the steel is mostly hidden from view. Carbon steel and stainless steel are both highly useful, but the chromium coating that covers stainless steel ensures that the steel does not rust or corrode when exposed to air and water. Over time, stainless steel retains its decorative luster with little maintenance, while carbon steel will rust overnight if left exposed to water or air without proper treatment.
Perhaps the easiest way to consider the differences between carbon steel and stainless steel is to think of the various consumer brands of pots and pans. Stainless steel pots and pans are marketed based on convenience. The coating on the steel means that the pots and pans are easier to clean, do not stain and will not rust if left sitting in the sink. A set of stainless steel pots will continue to look attractive for as long as the coating on the steel remains effective.
Carbon steel pots and pans, conversely, are used by professional cooks. These products are not as decorative and require much more maintenance, but carbon steel gets hotter than stainless steel and distributes heat better. Typically, these types of pots and pans are less expensive and more durable than stainless steel.
For example, most professional woks are made of carbon steel. To properly use this type of wok, the metal must be heated and treated with oil to protect the surface and cleaned immediately after use. It will rust overnight if left uncleaned in the sink. Since the steel has no coating, it will also retain the flavor of the food that is ordinarily cooked in it. People who use woks often feel that the carbon steel version gets hotter, distributes the heat evenly so food does not burn and makes the food taste better because of the seasoning of the metal.