Drug substance:The active ingredient intended to diagnose,treat,cure,or prevent disease or affect the structure or function of the body,excluding other inactive substances used in the drug product.
Drug Products:The finished dosage form (tablet,capsule,etc.) that contains a drug substance--generally,but not necessarily,in association with other active or inactive ingredients.
简言之,前者就是那些可以药用的物质,比如人参、枸杞或其它化学物质.而后者只是最终制成的你可以服用的药,它们可以含drug substance,但并非必须,也可能含有本身没有药用的物质.