This is the order from easy to hard: 3 1 2 4.
Ballade #3: The Ballade doesn't get too difficult but it also
doesn't get easy.
Ballade #1: About half of the Ballade is easy but some parts are
difficult.
Ballade #2: The Ballade starts with a super easy warm up, and
suddenly the part gets far too difficult. After that, it gets a
little easier. It continues to get more difficult until the Ballade
is way too difficult, and it ends smoothly (Shortest Ballade).
Ballade #4: 95% of the Ballade is really difficult, but it can't
be as difficult as the super difficult part on Ballade #2. The 5%
of the Ballade is really easy. At one point, the Ballade stops for
a long time, and then it continues and ends (May be the longest
Ballade).