Hey bigh, I also responded to your review!

There are 2 differences between hard and easy mode:

1) Size of puzzles

HARD MODE:

1st girl: 3x3 | 3x3 | 3x3 | 3x3
2nd girl: 3x3 | 3x3 | 3x3 | 4x4
3rd girl: 3x3 | 3x3 | 4x4 | 4x4
4th girl: 3x3 | 4x4 | 4x4 | 4x4
5th girl: 4x4 | 4x4 | 4x4 | 4x4
6th girl: 4x4 | 4x4 | 4x4 | 5x5
7th girl: 4x4 | 4x4 | 5x5 | 5x5
8th girl: 4x4 | 5x5 | 5x5 | 5x5
9th girl: 5x5 | 5x5 | 5x5 | 5x5
10th girl: 5x5 | 5x5 | 5x5 | 6x6

EASY MODE:

1st girl: 4x4 | 4x4 | 4x4 | 4x4
2nd girl: 4x4 | 4x4 | 4x4 | 5x5
3rd girl: 4x4 | 4x4 | 5x5 | 5x5
4th girl: 4x4 | 5x5 | 5x5 | 5x5
5th girl: 5x5 | 5x5 | 5x5 | 5x5
6th girl: 5x5 | 5x5 | 5x5 | 6x6
7th girl: 5x5 | 5x5 | 6x6 | 6x6
8th girl: 5x5 | 6x6 | 6x6 | 6x6
9th girl: 6x6 | 6x6 | 6x6 | 6x6
10th girl: 6x6 | 6x6 | 6x6 | 7x7

2) Movement type

Easy mode - you can move puzzles freely, for example: you can switch top right square with top left square

Hard mode - you can swap only adjacent pieces, so if you want to switch top right square with top left square, you wouldn't be able to, you can only move the pieces close to each other

Wish you good health, stay safe!

Is the hard and the easy mode flipped somehow?

This is indeed the thought process we had during the development - should we make hard mode a Dark Souls of puzzles or just a little more tricky than easy? We decided to keep it achievable since this is mainly a game for pleasure. So in hard mode we came up with the idea of making only the adjacent pieces move but decreased the number of squares starting with 3x3 instead of 4x4 or even 5x5 - which was the first idea ;)