Just some points I came up with
The HSC may seem easier content wise (or at least for me- I study a health science) simply because you've spent years building on the same subjects. It took me a while to get my head around some of the uni content because it was something I had NEVER encountered before.
However, the HSC was more stressful in that you may have been aiming for "that one atar/mark" and you feel as though everything counts toward it. I aimed to pass this year in uni
Uni may seem harder as well with the marking (though this varies). I'm still learning how best to write essays/short answers because what they like can depend on the individual lecturer
Which leads me to marks. I was aiming for and achieving 85-90+ in most of my assessments during highschool and would have been shattered at anything under 80 (well, in most subjects). My essays in highschool used to always be a high band 5 at the least. Last year I got my first uni essay back and got something like a 65-70. Looking back, that was a pretty good attempt! You have to readjust your understanding of the marking systems, in some courses/units a 90 is VERY difficult to obtain.
Finally, as others have said, uni can be stressful because of other commitments. I found that I burnt-out after the hsc and didn't set my usual standards. Whilst toning down the mark expectations was a good thing, the procrastination was not. I found most of my uni stress last year could have been avoided by simply making regular lecture notes and (shock horror!) doing the readings.
You've made it through the HSC- congrats! Don't approach uni as something to be feared or something very difficult. Approach it as a new learning experience. Best wishes
