I assume you are referring to cable glands, which are used to attach and secure electrical cables to equipment or enclosures.
Below are the main Differences Between 20 and 20s Gland
The main difference between a 20 and 20S gland is the design and the intended use. A 20 gland is a standard cable gland that is typically used for non-armoured cables in general-purpose applications. It is designed to provide a seal around the cable to prevent the ingress of dust, moisture, and other contaminants into the equipment or enclosure.
On the other hand, a 20S gland is a specialized cable gland that is designed for use with steel-wire armoured (SWA) cables, which have a layer of steel wire around the cable to provide additional mechanical protection. The 20S gland has a unique design that allows it to securely clamp the armour layer of the cable, in addition to providing the same sealing function as the standard 20 gland.
In summary, the main difference between a 20 and 20S gland is the intended use, with the 20S gland being designed specifically for use with SWA cables and providing additional mechanical protection in addition to the sealing function provided by the standard 20 gland.