What's the difference between Normal and Hard?

I've finished Normal and almost finished Hard and I haven't noticed any differences between them. Is Hard actually harder?

after several playthroughs the difference doesn't appear very significant, but the jump steering/handling of the ball is more tricky in the harder version, which is the main difference. there are also slight variations to the tower puzzle (where you get ).

Also in some other puzzles. Like laser speeds in the underwater lab. Could've also been how fast fireballs spawn from lava pits, not too certain of this though.

Yes, I remember the lava pits spawning way more fireballs.

To me lava pits seemed to spawn fireballs at exactly the same rate. The lasers in Cliche lab were the most noticable difference. They were much faster.