The thickness of ZLC is about 5.6mm, while the ZLF is about 5.4mm. Weight wise ZLC is approximately 5g heavier than ZLF. I feel that the ZLF is softer and provide extra dwell time than ZLC, which makes ZLC faster than ZLF. The F indicates Fibre in the composition of the blade, which has an elastic characteristics...while ZLC indicates a combination of Carbon and ZL Fibre.
I also feel that ZLF provides better control thus allowing more spin, maybe because of the increased dwell time, while the ZLC though it generates a little less spin, it compensates by providing more speed. The rubber I used for both blades were Stiga Calibra LT Plus (FH) and Stiga BoostsTP (BH). I prefer the ZLC as it suits my style of play, but it still not as fast as my Stiga NCT Hybrid Wood.
Hope the info helps buddy.