I think it gets more difficult, especially with topics such as Motion and Applications of GP.
It also appears to get harder because a fair number of teachers will be trying to cram content (2U is a very content-heavy subject, lots of topics but not too much depth) to meet deadlines ie: Trials.
But it really does depend on your school topic order.
Both were the same difficulty to me. Although, when I compare the questions in the hsc paper with the questions in my yr 11 yearly, I'd say it gets quite a bit harder.
I was able to study both the year 11 and year 12 content in one year without much difficulty.
As long as you're motivated and put in a bit of effort you'll be fine Good luck!