We have different release channels.
- developer is a version we build for our self, i.e. the developers. This can be anything, a bug fix, some technical Voodoo etc.
- alpha is a version we consider "good enough" for testers
- beta is what we "allow" users to test
If you are a tester and you are not sure, you can always ask.
So if you are a tester, you can install multiple versions in parallel and the use the wizard to copy your model set around. This feature was maybe confusing during the first installation, but now will help you as you can copy your settings etc. among multiple installations.