Personally I prefer the leetcode UI, but I find that AoC challenges are usually grokkable problems where leetcode seems to require you to have a ton of very bespoke data structure and algorithmic knowledge that simply doesn't have a purpose for me besides doing more leetcode
Yes, I think this is the major difference. LC are specifically geared to test DS&A knowledge: trees, graphs, DP, BFS, DFS, greedy, etc. AoC are more about iterating fast to solve it however.
