It may be different in your country, but in the west "Alpha" is used to describe software that is not feature-complete and is usually unstable and a long way from completion. It is often released to testers/early access adopters in order to gain feedback for the ongoing development of the game. Alpha software can change drastically between alpha and gold releases.
Beta software, on the other hand, is usually used to describe software that it feature-complete and almost ready for release. Beta software's functions/mechanics/etc. are all locked in and the only things that will change between beta and gold release are balancing changes and bug fixes.
Companies putting "beta" on their games is actually the publicity stunt in most cases these days. They'll either release an incomplete game for full price and then claim "oh, but it's beta" or else they'll release a "beta" two days before the gold release (in which case it's not a beta, it's a demo).
Hope that answers your question :)