Actually, there's an enormous difference. Disc is designed for high capacity, and thus has insanely high bit densities. They rely on significant technology to work at all. With the bits so small and packed so close together, modern hard disks tend to self-destruct if not constantly maintained. (read: powered on and left to run recalibrations) Tape is designed for long term storage, so bigger bits, less densely packed. Tape will maintain the pattern written to it for a very long time.
If your tape drive doesn't work, it can be replaced (usually -- older tech can be a problem), and the tape(s) read perfectly from it. When your hard drive fails -- bearings, circuits, or (99.999999% of the time) the firmware the cheap bastards stored on the media becomes unreadable -- You. Are. Screwed. (options: 1) throw it away, 2) pay a data recovery company $$$$ to get your data back.)
Flash drives aren't magnetic storage.
Enterprises use disc backups for two simple reasons: cost and speed. In most cases, the data backed up will be obsolete in a few weeks or months. Anything that has to outlast the quarter finds it's way to more stable storage -- tape, cd/dvd/bluray (unwise, but still used), flash drives, and/or SSDs.