Question about Hard Mode

Ok so I just Started a NG+ for FF4 on Hard mode after beating it on Easy now I admit I’m a very casual gamer and Hate challenges but the Completionist part of me really wanted that sweet alternate ending only unlocked in hard mode + the 2nd playthrough unlocks as well but here are my questions

1. How much changes in hard mode

2. Do the puzzles (like Piano puzzle and >! Sakura’s Diary 3 !<) change at all or is everything pretty much the same

3. Any other big differences?