Full Idea
The notion of ground should be distinguished from the strict notion of reduction. A statement of reduction implies the unreality of what is reduced, but a statement of ground does not.
Gist of Idea
The notion of reduction (unlike that of 'ground') implies the unreality of what is reduced
Source
Kit Fine (The Question of Realism [2001], 5)
Book Reference
-: 'Philosophers' Imprint' [-], p.15
A Reaction
That seems like a bit of a caricature of reduction. If you see a grey cloud and it reduces to a swarm of mosquitoes, you do not say that the cloud was 'unreal'. Fine is setting up a stall for 'ground' in the metaphysical market. We all seek structure.