123801 is TRS22 SP3 or TRS22 PE SP3
123794 is both the current Trainz Plus Stable build and the Trainz Plus Beta build. There hasn't been a beta release since the release of the last stable build of Trainz Plus. It seems that the policy of releasing WIP builds is not being followed any more. The recent newsletter hinted that a new release of Trainz Plus is forthcoming real soon now™.