FreeBSD: diff between RELEASE and STABLE

[stormjumper]

hi,

i'm slightly confused by the use of the terms RELEASE and STABLE.

specifically, i refer to section/chapter 2 at the FreeBSD Early Adopter's
Guide at
    http://www.freebsd.org/releases/5.1R/early-adopter.html
where it states that
"At the moment, only one STABLE branch is under active development; this
branch is referred to as ``4-STABLE'', and all of the FreeBSD 4.X releases
were based on it."

yet 4.9 is the production release, and is referred to as a release at
    http://www.freebsd.org

can anyone explain the two terms in a less confusing way?

also, is 4.9 the stable release or not?

thanks