Oriental Reed Warbler Singing

Oriental Reed Warbler(Acrocephalus orientalis) is a summer visitor in Japan.
They are noisy birds, and you can easily locate where they are singing near the reed bed.
At first, I thought all the song sounded the same way.
But there are some difference in their repertoires,
so I recorded two individual birds' song and compared.
The first one was on top of the tree, so I could see him very well.
The other one was behind the reed, and I could't see him
but he was very close.
Saitama, Japan