What is the difference between `Sid' and `unstable' ?

[Jerome BENOIT <jgmbenoit@wanadoo.fr>]

Hello List,

I have just tried to install vim-gnome (sid):
for that you neede  vim 1:6.2 (unstable)

My point is: if in my `/etc/apt/preference/' file
I ask to fetch the `vim' package from `Sid',
I do not get it with `dselect',
but if I ask to fetch the `vim' package from `unstable',
I get it !
Note that my `/etc/apt/sources.list' data file
reaches both `Sid' and `unstable'.

So what is the difference between `Sid' and `unstable' ?

Thanks,
jerome