By tracked, I mean my camera was mounted on an equatorial mount driven by motors that counteract the rotation of the Earth. This works well when you can achieve good polar alignment. (meaning your mount is exactly facing celestial north). It's fairly hard to get right, and I spend a considerable amount of time working on it. It allows me to take a 30 sec exposure (or longer) @ 200mm, without it I would be limited to about 2 sec @ 200mm.
Auto guiding is the next level up, by which another camera is mounted along side your scope (or whatever main lens you are imaging through), and hooked up to software that will follow a reference star, sending correction data to the motors on the mount, adjusting for any errors in tracking. At least that's how I understand it, maybe someone more experienced could fill in anything I missed. I don't have one of those systems, way out of my budget!
That is an accurate description of guiding, though they're not necessarily as expensive as you appear to think. I guide with an $80 finderscope, $90 (IIRC) webcam and free software on my cheap laptop. Of course you can spend much more if you want, just like you can for your tracking mount.
Nice job with your non-guided tracking; that's a great shot!