Mac OS has it's own filesystem called HFS (Hierarchical File System), the one used in OS X and since System 7 (I think, maybe it started with OS 8) is HFS+.
MacOS X is not Linux, you will find that out once you'll get yours. It is UNIX-based, just like Linux is, but except that, there are huge differences.
You will see that a couple of Linux commands will work, you will not be totally lost in the Terminal, but you will also find out that it is not the best way to use OS X through the Terminal, and it is not meant to.
MacOS is all about GUI, since System 1. And eventhough OS X is UNIX-based, Aqua (the OS X GUI) is part of the system, totally integrated, unlike Gnome or KDE on Linux.
And that's the way it has been developped, to be used with a mouse through the GUI.
