The following beta versions exist:
The X prerelease versions are labelled using characters from the Greek alphabet, while the PC versions are labelled using characters from the Hebrew alphabet.
About what has changed: 2.00 beta is an improvement over 2.00 Alpha that lets both the Titrax program and the Sumtitra script write and read new (PC-compatible) data files. In Alpha, only the titrax program was upgraded.