SunOS and Solaris

SunOS is a Sun Microsystems implementation of the Unix operating system. Solaris is SunOS packaged with a number of additional tools and a graphical user interface (GUI) environment. Since Sun Microsystems did not offer Solaris until SunOS 4, SunOS and Solaris have different version conventions (e.g., Solaris 1 includes SunOS 4, while Solaris 2 includes SunOS 5). To further confuse the naming scheme, Sun now refers to Solaris by just its point release (e.g., Solaris 7, 8, or 9 instead of 2.7, 2.8, or 2.9).

Up through version 4.1.x (Solaris 1.x), SunOS was a heavily BSD-influenced Unix implementation. However, in the late 1980s, Sun entered into a partnership with AT&T, which was then developing the other major Unix flavor, System V. The result was System V release 4 (SVR4), which incorporated BSD as well as SunOS extensions (e.g., NFS). Subsequently, with its version 5.x (Solaris 2.x) releases, SunOS shifted from its BSD origins to SVR4.

In common parlance, when people speak of SunOS, they usually mean the older BSD-based versions (SunOS 1 through 4.1.x and Solaris 1.x). The term "Solaris" typically refers to the SVR4 releases (SunOS version 5 and higher, and Solaris version 2 and higher) exclusively.