Awhile back, we mentioned that the Mac OS 8.1 version of Disk First Aid is a considerably larger file than any previous version. We speculated that this had to due with its support for HFS Plus. We contacted Apple for confirmation of this and recently received a reply:
First, noting a related matter that the version of Disk First Aid on the 8.1 Disk Tools disk is smaller than the main 8.1 version of DFA, Apple said: "The reason for this difference is just resource chopping to make it fit on the disk. None of the removed resources affect operation, and the two versions are functionally identical."
As to the difference between the main 8.1 version and all previous versions, Apple will be explaining this is a forthcoming TIL file and/or Technote.