Simply known as OS, the next generation operating system for the Molecular, was a development from LOS. Fundamentally, the OS was still required to do all that LOS did.
Bob Doncaster took over the core OS development from Joe Templeman, and Mick Benham wrote all the utilities.
Any code written for LOS would run under OS without modification - assuming the original programmer didn't do too anything weird!
(I seem to remember when moving data files from LOS to OS, they needed to be moved to an even address??)
There were some important and often welcome changes:
Support for CDC Lark Drives and the SMD Controller
Support for the 4 channel serial i/o cards
Much friendlier utilities for the programmer and support people. Much more verbose and generally menu driven.