I can barely year 10...gee I am getting old...the gap was big, but manageable.
In comparison, year 11 was extremely busy for me, only because I had much more extra curricular and school events (i.e. camps, excursions, etc.) The first term was horrendous. Year 10 was quite chill, even though I didn't think so at the time. In retrospect, I wish I freaked out less.
Year 11 really teaches you have to manage your time better and make sure you get things done. Use year 11 as an opportunity to improve your organisational skills, experiment with different study techniques to see what works best, etc. I'm in year 12 now, and I've only just found a system that works for me, in terms of organising my work, and found it much more productive. Try not to last-minute in year 11.
Content wise, you will find year 11 is a lot more intensive and detailed. English, imo, is a lot more structured in year 11 and use it as an opportunity to perfect your essays and creative writing. It depends on what subjects you do, but I found all my subjects more intensive.
Timetable wise, I had free periods, which were the best part of my day. You'll learn to love and enjoy your frees, which is one of the benefits of year 11. You will also have more time to work on subjects you actually care about too.
Pretty much, just use year 11 as the time to get your organisational skills sorted, and put effort (at least a little bit) for year 11. If you can manage your time well enough, you will find the "gap" small.