Why is this sequence of moves incorrect for this puzzle?
http://en.lichess.org/6BtIbKZJ1.gxh6 Kxf3 2.h7 Bxb3 3.h8=Q d3
The variation is also win for white.
1.g6 Kxf3 2.f7 Ke4 3.f8=Q b4
I think Stockfish evaluated the latter was superior.
It's difficult to explain it. It's better to solve other puzzles without worrying about it.
gxh6 is a clear win even with primitive moves after it:
http://en.lichess.org/s4U3eve6