[E-Reader] Does somebody know what exact compression Nintendo used for VPK files?

[Sunicune]

Hi there People!

I've been using Caitsith2's nevpk compression tool to compress and decompress .vpk files.
While I was decompressing and compressing I noticed that the .vpk files looked different when I compressed them again.
I know that Nintendo used some kind of compression called LZ-Huffman.

Now my question is: Does somebody know how EXACTLY Nintendo compressed them? Can it be achieved with Caitsith2's tool?
And does it have something to do with the LZwindow and the LZsize? Which values are the ones Nintendo used?

I thank you in advance for replying and your time!

Greetings,

Sunicune