OpenVPS is a set of software built on top of the Linux VServer aimed specifically at Web Hosting. It is not another set of kernel patches, but a set of scripts to create virtual servers, collect resource utilization information, and provide an interface to the customer as well as the administrator.
The Linux ABI is a patch to the Linux kernel that allows a linux system to run foreign binaries. It was developed as a follow-on to the iBCS/iBCS2 project for the older 2.2 kernel. It supports binaries from SCO OpenServer, SCO OpenDesktop, SCO Unix 3.x, SCO Xenix 386, SCO Xenix 286 (with userspace x286 emulation), SCO UnixWare 7, Caldera OpenUnix 8, SUN Solaris 2, System V Release 3 (SVR3), System V Release 4 (SVR4), Wyse V/386, and ISC Interactive Unix. Only the Intel i386 platform is currently supported