The SR prefix stands for the Silver Oxide chemistry. The LR prefix indicates an Alkaline chemistry, which makes the battery cheaper and of about a third of the mili-Amp capacity (mAh) of a Silver Oxide battery.
When the three-digit model name of Silver Oxide battery begins with a 3, the equivalent three-digit Alkaline Watch battery begins with a 1.
The SW suffix indicates low-drainage, meaning that the battery will spend the energy slower. It is best for devices that pull a low current. High-drain devices will consume faster the battery charge, and require batteries with the W suffix.