[lubuntu] Network without samba works but....

I always thought Samba was a prerequisite to access to any windows share (same home LAN).
But everything works well without it. PcManFM ask me credentials, I'll put them and I'm in.
Most of shared folders work fine, some list very few files (when it supposed to be several in there).
I'm on lubuntu 15.10.

First question: why shares works? (for knowledge, I'm happy for this xD)
Second question: why most of files are not listed in some folders?

(p.s.: there's a thread similar to this I did some days ago, but there I had samba installed, so opened a new one)