Moderation, alignment and scaling are all different processes. NESA performs moderation and alignment, while UAC performs scaling. Moderation is the process that NESA uses to determine the Assessment Mark, which is the mark that reflects your internal performance and contributes 50% of your overall HSC mark for a subject. Moderation essentially considers students' ranks within their school cohort alongside HSC exam marks achieved by their school cohort to determine Assessment Marks.
On the other hand, alignment is a process that modifies a raw HSC exam mark simply to indicate a student's level of performance against the different band descriptors in a subject. This produces an aligned HSC exam mark, and is the mark that is reported to students. Unlike moderation, alignment has no effect on a student's ATAR, because aligned marks are not used in the calculation of ATARs.
This brings us to scaling, which is the process that is performed as part of determining a student's ATAR and occurs after the moderation process. UAC takes a moderated Assessment Mark as well as a raw HSC exam mark (i.e. neither mark is not subject to alignment), producing a raw HSC mark. This is the mark that UAC scales, resulting in a scaled HSC mark to be then used in determining the student's ATAR.
I hope this helps!