Classification of Benz Micro cartridges

A question for you Benz experts. I am confused by the classification. As I understand it, the Ruby/Ebony L and H, sit just below the LP S as the reference cartridge. Fine so far, then what is the LP? Is it an older version of the LP S or another cartridge sitting at the same level as the Ruby and Ebony?
Before anyone makes the sensible suggestion of contacting the US distributor, I am in the UK and we don't seem to have a supplier I can find. Their website is not helpful on this point. Thanks