Originally Posted by Penforhire
But SD cards are just one form of flash memory. They have different controllers but I believe the semiconductor construction is the same. Whatever else you are using is just as likely (or unlikely) to be corrupted by metal detectors in the powered-off state, isn't it?
I have read there is huge variance in the resulting quality of flash memory. Some cells go bad after only a few thousand write/read cycles. It depends on the fabrication processes used (some manufactures are better than others). Recent research is pointing toward extending flash lifespan by adding a microscopic heater circuit. Exciting times!
Not only the controller is different (slower), the ECC is way lower (Error correction), as well as the construction of SD cards is more volatile to both heat and mechanical abuse than a USB stick.
Quite some chinese card readers put the full 5V USB voltage on SD cards (they operate at 3.6V), thus overheating the device and resulting in shortened life.
USB sticks always will have a 5V input, regardless of on which computer you plug it in (provided it's not a broken one).