The A3000UX is essentially the same machine as the standard A3000, however it was labelled A3000UX because it was shipped with an alternative UNIX operating system called Commodore Amiga UNIX, affectionately known as Amix. Amix was a full port of AT&T's System V SVR4 UNIX and included the X Window System which is a server for hosting graphical environments and the Open Look graphical interface. The A3000UX only ever used versions of the A3000 motherboard which contained an 030@25Mhz and a 68882@25Mhz (as opposed to an 030@16Mhz and 68881@16Mhz) and was usually shipped with the Commodore 3070 tape drive and a three button mouse. Other Amigas were generally shipped with two button mice. Optionally the A2410 graphics card, A2065 Ethernet card and the A2232 multi-port serial card were also shipped with the machine. The A3000UX is fully capable of running AmigaOS in every way the "normal" A3000 is but was supplied with the special Kickstart 1.4 ROMs that were designed to either boot UNIX or load the real Kickstart from a file. Shortly after release, Sun Microsystems, a major UNIX vendor was interested in rebadging the A3000UX for supplying as an entry level UNIX workstation. Unfortunately in true Commodore style, the deal fell through.
The following links are pictures and an info leaflet from Commodore about the A3000UX.
Please see the A3000.