Michael Chare wrote:
Some angle grinder disks are intended for metal and others for stone.

Can anyone explain what the difference in the disks actually is, i.e. what
property of the disk makes it suitable for either metal or stone. What are the
disadvantages of using the wrong type of disk?

Is it in anyway dangerous to use the wrong type of disk? The labels on some of
my used disks are none to clear.

In general, there isn't much danger.
It's a matter of cutting speed, and life.
Disks designed for stone won't cut metal well, or will wear fast.
The exception is 'smeary' metals like aluminium and copper - they may load
up on some disks, and not actually cut at all.