Question [Q]Directory Tree in KitKat

Hallo.

I cant manage the directory tree in Android 4.4.

So. I when I go to "sdcard" I have data which looks like data from internal sdcard (in compare with 4.1), but there's one more folder called "0" which also contains data which looks like data from internalSD, but its mounted as "emulated/0".

What does it exactly mean? Where will come data which I will copy from PC to internal SD, and where will come data which I will download (files, game files). I cant manage it Whats the emulated 0 directory?
In 4.1 was simple: "sdcard" for internal sd, "ext_sd" for external sdcard, mounted as "mnt/sdcard0" and "mnt/sdcard1" but here I can't match mount points to memory.
Nothing in my life can scare me, I have children.