Ahh, you want to know which one of those two to buy, is that the question? Right now you don't have any, and you are going to buy one stick of refurbished memory? If the first is a single stick and the second two sticks, buy the second. Running matching memory in both channels on your motherboard will give you better performance.
If both are single-stick, I have no idea. Just make sure that the specs, including voltage, match the board that you are going to put them in!