The basic difference between "organic" and "inorganic" acids its the presence of the carbonile function, which means presence of a C atom in the molecule.
Usually the "organic acids" are weaker than the "inorganic ones", but after all, its relative to operating conditions, active surface, etc.
I don't know which kind of coatings you're seaching for, but some times this substances are made from organic groups that -like amines, for instance- may react with weak acids and create a "hot spot" for corrosion.