Here's a summary of all the early drafts of the bitcoin paper known so far: https://www.gwern.net/docs/bitcoin/2008-nakamoto
I think that contains all the details relevant to this discussion.
I wonder if people have searched in the blockchain itself. The 2009 white paper lives there.
You can get it like this:
The idea that there's something hidden in the paper makes it really interesting, although I don't think there's anything in there...
About the "Chinese characters" in the original Bitcoin paper, I think that could just be Notepad interpreting the pdf data as random Chinese symbols as default. You don't see that in Linux for example, and that might explain why the text itself is nonsense. Also, you're comparing a pdf made with v1.7 with one made with v1.4 (bitcoin.pdf) so there might be big differences in the structure of the pdf files, which might explain what you see.
https://en.wikipedia.org/wiki/History_of_PDF
Here are a few metadata details about the discussed files:
PDF Version : 1.4
Linearized : No
Page Count : 8
Language : en-GB
Creator : Writer
Producer : OpenOffice.org 2.4
Create Date : 2008:10:03 13:49:58-07:00
PDF Version : 1.4
Linearized : No
Page Count : 9
Language : en-GB
Creator : Writer
Producer : OpenOffice.org 2.4
Create Date : 2009:03:24 11:33:15-06:00
PDF Version : 1.6
Linearized : Yes
Page Count : 8
Language : en-GB
Creator : Writer
Producer : OpenOffice.org 2.4
Create Date : 2017:08:26 18:31:20-04:00
Also ecash.pdf reveals the use of a library that allows editing metadata, Adobe XMP:
With that tool you can edit any metadata in a file, so it can't really be trusted at all as genuine. Maybe it is, but it's not possible to know anything else has changed. Also the pdf property linearized was set to No in the early drafts but set as Yes in ecash.pdf. It might be that they forgot to match that field.
Also, if we focus on the pdf version, we can see that ecash.pdf was probably created in another computer, or application, which used a more modern version of the pdf standard (v1.6 vs v1.4). It's really strange to see that the file was supposedly created with the same version of Open Office, v2.4, but the pdf version of the created file doesn't match. A quick search on the source code of Open Office 2.4 shows that they indeed use pdf v1.4 in that version of the software: