These are small sites which only accept a maximum of 5 caravans but can often have more pitches than the 5 which allows a more spacious caravaning experience. See the acerage to pitches entry in the listing and swap to satellite view on the map to get a more detailed idea of the site you are looking at.
Some CL/CS Caravan Sites are very basic but others can have all the bells and whistles. You must be a member of the relevant club to use them.
Prices vary, they are usually priced below the larger club sites.