The difference between a flash drive and a thumb drive is that flash drives can also be SD Cards and other similar devices and thumb drives also known as USB sticks are a type of flash drive.
Some flash drives have larger storage capacities to them than thumb drives or USB memory sticks.
Thumb drives and USB sticks also use flash memory to store the data.
Thumb drives and USB sticks are small enough to fit in your pocket and some flash drives can be larger.
An SD card is also a small type of flash drive.
The lifespan of a USB memory stick is around 10 years.
However some USB memory sticks may last longer than 10 years and some USB memory sticks may last less time.
The actual lifespan of the USB memory stick also depends on the write cycles and erase cycles.
The more write cycles and erase cycles on the USB memory stick the shorter it's lifespan.
USB memory sticks can handle between 10,000 to 100,000 write and erase cycles depending on the USB memory stick.
The number of the write cycles on the USB memory stick also affects how likely the data on the USB memory stick is to deteriorate.
The cheaper models of USB memory sticks tend to have shorter lifespans and the more expensive USB memory sticks tend to last longer.
USB memory sticks or flash drives can also fail prematurely if they get abused or are exposed to any extreme temperatures or humidity.
The signs that your USB memory stick are failing are the files are unreadable or inaccessible, the available space on the USB memory stick is less than advertised, the computer doesn't recognize the USB memory stick and the read and write cycles of the USB memory stick are slower than normal.
To extend the lifespan of your USB memory stick you should eject the USB memory stick before removing it, keep it in a good safe place, avoid exposing the USB memory stick to any humidity or extreme temperatures and if possible use high quality USB memory sticks or flash drives which use Grade A memory.
After 10 years I would not rely too much on the USB memory stick for keeping the data safe.
Always backup your data on multiple drives and memory sticks to have copies in case the USB memory stick or one drive happens to fail.
I back my data up on multiple drives, online and offline and don't rely on just one memory stick or hard drive to store data.