This is some determination right there! In this LD compo build, the main difference between the difficulty levels is an enemy progression.
Easy becomes quite hard on 25-35 minute of the game. So if you didn’t manage to win before that, it’s hell on Earth basically. Therefore, you outdamaged the hard-difficulty waves, which is impressive. This blocking-your-own-troops tactic is interesting.
These difficulties were added in the last minutes to make the default playthrough at least a bit easier. I tested the game on normal all the time and it takes 15-20 minutes to win there. Hard difficulty is ~impossible, but I can get close to the victory. I can beat it on Hard if I cheese the game a bit, but it’s not as interesting. :)