High capacity USB flash drive vs USB HDD - NAS backup.

[OverDrive]

What are the advantages/disadvantages of using one of these high capacity USB flash drives over a USB HDD?

I'm thinking I could keep one permanently plugged into the back of my NAS for backup. I would ensure that my USB HDD still continues to form part of my backup strategy.

I've seen some very cheap non-branded high capacity drives - what's the catch? Bad NAND?

Thanks.

 

[OverDrive]

Thanks for the reply. Agreed, I always disconnect my USB HDD after a backup operation and store it away safely. I was just thinking of a flash drive as a secondary backup medium.

At the moment, my documents are stored on OneDrive and I have bi-directional sync setup on my Synology NAS. However, my photo/video/audio files are not syncing with any cloud service. Any suggestions?