Flash Drives, Memory Stick, Pen Drives, USB Drives and other names you can think of. They are all the same thing. A small piece of solid state memory, that you stick in a USB slot and transfer data to and from a computer/laptop. They can last as long as anything else, days, weeks, years.
They are very easily corruptible, either by dropping them, putting them near magnetic influences or not switching them off properly before removing them.
They were never designed for or meant to be used for long term storage, as according to some of the questions you get on here, people have found out to their cost when they have lost important data using them.
Their primary design and purpose was to just transfer data from one computer to another or for logging on purposes. They basically just replaced the old floppy drive disc that was used for the same thing a few years back.