Traditional coatings of steel elements consist of the following layers: ground (priming) and superficial.
Ground paint always plays a role of anticorrosion protection. Some parts of an item are less corrosion resistant, e.g.  welded, flash-welded and soldered joints as well as bends need a double layer of anticorrosion primer for protection.
Priming and superficial layers are made of enamels or decorative paints. The priming layer guarantees adherence and the life of a coating, whereas the superficial one decides about the final look and resistance of an item.
Ground colour and enamel or superficial paint must always match. This ensures adherence and, as a result, the life and strength of a coating. 
The coatings of the galvanized steel items usually consist of two layers, as the role of the anticorrosion primer already plays galvanizing.