Cold rolled steel is essentially hot rolled steel that has been through further processing. Once hot rolled steel has cooled, it is then re-rolled at room temperature to achieve more exact dimensions and better surface qualities.
Cold rolled steel can often be identified by the following characteristics:
Better, more finished surfaces with closer tolerances
Smooth surfaces that are often oily to the touch
Bars are true and square, and often have well-defined edges and corners
Tubes have better concentric uniformity and straightness