There are many versions of the S60 platform (formerly known as "Series 60").
The first version was Series 60 v0.9 and the only device based on that release was the 7650.
Every version can have several feature packs (FP). They denote new features added to the specific version.
List of all Editions & Feature packs (the newest is on the top):
- S60 3rd Edition, FP 1 (S60 3.1)
- S60 3rd Edition (S60 3.0)
- S60 2nd Edition, FP 3 (S60 2.8)
- S60 2nd Edition, FP 2 (S60 2.6)
- S60 2nd Edition, FP 1 (S60 2.1)
- S60 2nd Edition (S60 2.0)
- S60 1st Edition (S60 1.2)
- Series 60 0.9
See also http://www.s60.com/