What's the difference between galvanised brake cables versus stainless steel?

I refurbish old bikes, and it's very common for cheaper machines to have cables rusted badly...The better iron usually comes equipped with stainless and they normally look fine even if the bike has been sitting out in the weather for several seasons.

I am sure you get the material science part - stainless steel does not rust. However, the cables on my bike are due for replacement right now and none of them have rusted. Frayed ends, outers that route badly (to get cracked), non-existent end-caps and outers that compress also come into the equation.

I will be swapping my worn-but-posh cables for properly assembled cables soon and I will go for cheap and cheerful (within limits). I advise that you do the same. With the money saved you will be more willing to swap them out next time you refurbish. New cables always trump old cables for shifting and braking and the steel being stainless or not makes very little practical difference.

I suspect, along with everything else, that SS cables produce less friction than galvanized. And for the price difference it's pretty silly to use anything but SS.