Alpha-lipoic acid consists of two different forms (isomers) that have vastly different properties. The "R" form is the biologically active component (native to the body) that is responsible for lipoic acid's phenomenal antioxidant effect. The "S" form is produced from chemical manufacture and is not very biologically active. Typical alpha-lipoic acid supplements consist of the "R" and "S" form in a 50/50 ratio. That means a 100 mg alpha-lipoic acid supplement is providing 50 mg of the biologically active "R" form. The human body normally produces and uses the "R" form of lipoic acid. This active form, R-lipoic acid, significantly supports healthy inflammatory response, is a potent free-radical scavenger and has been shown to be more potent than the combined "R" and "S" forms that comprise most alpha-lipoic acid supplements.
In other words, the R-ALA is a natural form as found in our bodies, and by buying the R-ALA you get almost 100% of the benefit (minus whatever they use for the coating). In the ordinary ALA you only get 50% of the natural form (R-ALA) and 50% of the chemically manufactured form, S-ALA, which is not particularly active. So with the ordinary capsules you need twice as many for the same benefit and also fill your body with chemicals.