This article is from the comp.sys.acorn FAQ, by Paul Vigay with numerous contributions by others.
RISC OS 3.8 was a developmental version of RISC OS 4 released to developers just before the closure of Acorn's Workstation division and cancellation of the Phoebe project. It was code-named Ursula (which is the name of Phoebe's twin sister in Friends!).
It has now been completed by the newly formed RISCOS Ltd and RISC OS 4 is the first new version of RISC OS to be released by a company other than Acorn, A comprehensive list of features was released onto their own web site during April 1999. This can be obtained from http://www.riscos.com/risc_os_4/Features.html
In a nutshell some of the major new features are:
* Performance Enhancements
* New Disc format brings new features, improved performance and more disc space.
* Redesigned icon set
* Faster/Easier configuration and !Boot
* New screen saver system
* 'Lazy Task Swapping'
* Improved applications including a new !Writer appliction for simple word processing and !Taborca - an Adobe PDF creator.