Here is an excerpt out of the Welding Handbook of Stainless Steel products from esab.
"Lime...coatings, also known as lime fluorspar or basic, are generally associated with the suffix -15 designation. They give the cleanest weld metal, which is usually the lowest oxygen and inclusions and are more resistant to moisture and porosity. The weld metal tends to be tougher, more ductile, more crack resistant and have higher corrosion resistance. They also have good all-position characteristics and are often chosen for site work. They are normally usable only with direct current and should be the choice of the most demanding applications.
AC-DC...coatings can be used with alternating or direct current and have the suffix -16. The major component is rutile, also known an titania, with some limestone which is why the coating type is sometimes referred to as basic-rutile. These AC-DC electrodes are the most popular type, and have the following characteristics: excellent starting properties are obtained with all types of AC welding equipment. The arc is stable, smooth, with fine spray weld metal transfer and the bead is uniform, flat or slightly concave with straight-line feathered edges. Penetration is complete and the weld metal is free from porosity. Slag is easily and completely removed without secondary film which means less cleaning, grinding and polishing time. Arcaloy AC-DC electrodes give good out-of-position characteristics. The mechanical properties of AC-DC weld metals are similar to weld metal from lime coated electrodes except it can be stronger with good ductility."
I have seen both E308L-15 and 16 produce similar results.
