Okay, as per title, which should I use and what're the pros and cons as I find that other than the slightly faster speed, flash drives are cheaper and more compact? Here's an example: WD 256GB My Passport SSD SanDisk SDCZ880-256G-G46 Extreme PRO 256GB Both are the same storage space and the price is similar. The only difference is the physical size and speed. So why pick one over the other? The use case would be to move my Photos library from my Mac onto one of these devices and probably some other files as it's taking too much space on my Mac. While at it, any online storage space recommendations, as I would like to have an online backup source for my photos as well.