ubuntu 9.10: What's the difference between “Unmount” and “Safely Remove Drive”?

Question

I always though that unmounting would flush the cache (if any) and it was then safe to remove the drive, but I see that there are two different options (and actually, sometimes eject shows up too, for a flash drive).

What are the differences, if any?

Answer 1

Unmount removes the drive from the root filesystem: e.g. if it was /media/flash it's no longer there, but you can mount it back. 'Safely remove' AFAIK does the same PLUS if powers the device off so external HDDs stop spinning