They work on very different levels, L-Cysteine is very unlikely to need supplementing if a good healthy nutrition plan is applied since it is very common and abundant in many foods, it represent a substrate for keratin formation and for glutathione production.
Saw palmetto has the ability to block an enzyme that converts testosterone into dihydrotestosterone (DHT), the latter of which is a more androgenic form and can cause hairloss in the genetically susceptible.
Saw palmetto may effect prostate growth as well.
Sting nettle root, pigeum bark and other plants are very similar to saw palmetto in their action and eventually may work in synergy.
They do work when applied topically too.