Difference between front struts for classic Sport and Classic Turbo

Hi I have 99 Sport which may need some new rear struts. Was thinking of doing all four (front and rear) using KYB Excel-Gs


According to the catalogue here
KYB – Online Catalogue for Shock Absorbers, Coil Springs and Kits the rear struts for the Sport and Turbo have the same part numbers, thus the same struts.

The Front Struts have different part numbers. Any ideas what the difference is? Is it damping rate? or piston length? or both?

Thanks