Aha.
In that case, it's a division of labor that goes something along the lines of what systems the technicians are responsible for. There are 'primary' and 'secondary' engineering systems. The duties of a technician do not change with their station, only what they're working on.
The Mainspace deals primarily with propulsion and ship's power and weaponry. They tend to spend a lot of their time hanging around in what I like to call the 'mainspace' - that place belowdecks with all the panels and shit - watching the power level of the capacitors and making sure that the auxiliary, combat, and propulsion systems have a proper load to operate with.
The Auxiliiary deals primarily (as I mentioned above) with ship's life support, health and comfort, and 'secondary' systems. This includes pretty much everything that isn't propulsion, weapons, or the power grid infrastructure.
As strange as this may sound, the work is actually fairly evenly divided - the primary systems require a lot of maintenance, monitoring, and upkeep due to the fact that Ketsururi tends to build more on a high-performance concept than basing their designs on safety, longevity, or ease of maintenance. The Auxiliary systems tend to be more 'stable' and, while they still require maintenance, it tends to run less along the lines of holy-shit-system-failure-explosion-ahhh! and more along the lines of the-damn-pipe-sprung-another-leak.
For a little further clarification on the difficulty of the mainspace position, consider that up until recently, the 'hole' was largely manned by disposable, programmable sprites. They were more or less expendable and few captains cared. Also, due to the advent and golden age of hyperspace drives, ships don't actually have to have the survivability they once would have had to have. Journeys that would have taken years, take hours. Why build an engine around any other concept? Really, I like to think of certain Yamataian ship systems as Trojans - they're only good once. Then you either have to switch them out (or maintain them, which is less applicable for comparison), or else they're probably going to break and you're going to be in a world of hurt.
In terms of superiority, they are both important jobs, but the Mainspace is, obviously, posted in the mainspace during battlestations. It is the responsibility of the mainspace supervisor to co-ordinate with the other engineers belowdecks, and to maintain communications with the bridge, because out of the two of you she has a better view of the overall condition of the systems most important to combat.
Also since this whole naming convention thing is getting on my nerves, just to make absolutely sure we're clear;
Code:
Nito Hei Kumiko Endoh Technician Mainspace
Nito Hei Takeda Junko Technician Auxiliary
Was that of any help?