Aligned marks are done by Board of Studies. They align the school marks (summarised by a mark out of 100) according to how you went in the HSC exam (which is also in a way, aligned)
eg. You may stuff up the HSC big time (but still comparatively well across the state). You may have also stuffed up school big-time. take english - your mark was 50 % at school but you came 1st. You end up getting an HSC exam mark of 90 % (because you were in the top say...10% of the state). They'll therefore shoot that 50 % straight to 90. (or less, depending on what position you were at school, and how your mark compared with that of your peers)
This, essentially is alignment.
Scaling is done by UAC and it's the crappy scam they got running where they bring your mark down according to what they think (or some say...calculate) are "high-quality candidature" subjects. The low-quality ones will get scaled down heaps, whereas the higher ones will be scaled down less and special cases occur where the subject marks might scale up (eg, 4 u maths)
These scaled marks go into an aggregate out of 500 and this is what they use to rank you and give you your UAI.