Here's how I perceive the whole alpha/beta/version ball of string.
Alpha - the bare skeleton of a program, very crash-prone, full of bugs and lacking many planned features.
Beta - all major planned features and adding minor features, lots of minor bugs, often still some major bugs
RC (Release Candidate) - all major features, most/all minor features, only minor/unknown bugs should remain
Release - all major features, all minor features, no known bugs (except maybe a couple that are proving really hard to fix)
Stable - no known bugs, or at least the few remaining known bugs are well-documented edge-cases with workarounds
Final - can mean Stable, can mean Release, can mean last minor revision of a particular version on the roadmap
Version - a numerical way of distinguishing that the software is different from the last time it was published, often in the form of a date (e.g. ymd 20120616), integer (e.g. build# 1234) or revision (e.g. major.minor 2.3) or combination (e.g. ymd.build or revision.build or y.major.minor.build)
Roadmap - a list of planned features sorted by planned version, at least in theory.
For a hypothetical example, Fooware 2014 build 5.4 Beta might be a program published in the year 2014, is the 5th major version of that program, which in turn has seen 4 minor revisions (added another minor feature and/or fixed some bugs since the 3rd minor revision) that is still in Beta (has a tendency to crash for at least six different reasons along with numerous edge case problems).
To further confuse things, Alpha/Beta/etc can refer to a particular version of a program, a range of versions of a program, or be a separate tag independent of the version numbering scheme, depending on the preference of the person(s) doing the naming. For example, if you see a roadmap with Fooware 2014.5.3 Stable followed by Fooware 2014.5.4 Beta, this is likely to mean that a new minor feature has been added that may/has introduced some new bugs as well.
