O OmniOS se parece com o sistema normal, o SmartOS é mais parecido com o sistema do tipo livecd
I've considered using OmniOS to let me do more things in the global zone (configuring CIFS was quite annoying!) but that's too much work and downtime for me right now. If I had to start over I might start there.
unhappy_mage, 2013-04-24
em: SmartOS "all-in-one"? - [H] ard | Fórum
Fonte: link
SmartOS is an extremely lean version of illumos, and it is not intended to occupy space on the filesystem. Rather it boots from a <2Gb image,either USB key, PXE network boot, or CDR image, and occupies space in RAM. The OS is kept off the filesystem to simplify upgrades - attach a new image and reboot. [...] One does not use the root system to work on the machine, only to configure and install Zones from which work is done. [...] If you prefer an illumOS distribution presents itself more like a CentOS server, you can try OmniOS.
Christopher Hogue, 2013-03-24
in: Por que o SmartOS no meu laboratório? - SmartOS
Fonte: link