The hsc mark is what nesa sends you on the morning of the day ATARS are released. These are am average of your moderated external and moderated internal mark. They will be under the column HSC Mark. The atar contribution is what UAC uses for ur top 10 units, usually 5 best subjects. It adds all the "atar contributions" up and u get a score out of 500. Then all these total scores are ranked for all students in the state and you get a rank, which is your ATAR.
In the image below for biology, the students moderated exam mark was 60 and moderated assessment mark was 62, hence hsc mark was 61. When compared to second image the 61 would be equivalent to 50.2. Hence it has impacted them negatively. However the only marks they ever see are the marks in the first image. and if you pay i think $60 per paper you get your raw exam mark which is then adjusted via an algorithm, different each year to become your EXAMINATION MARK, but ye. We can also see that the break even point for biology is 79 see second image. Thus you would need a 79+ to be positively impacted for biology, different for each subject. You never see your the atar contribution for the subjects, until UAC releases the data for that year, which will be slightly different to the table in image 2, but not too drastically and you calculate it yourself, but unnecessary to do so, as you would have gotten your atar by then.
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