iDontShift

Pantheon

kernel - window manager - firefox

since win7 it has been a unix like kernel, which is what linux is.

so at their heart is the kernel... both the same these days mostly, with a bunch of added services

windows 7 as you know it, is a window manager on top of that kernel

pantheon is a window manager, as is gnome, kde, xfce, lxme .. all these offer window decorations for you app (like the X in the corner and everything around the window that isn't part of the app . (some apps don't use 'window decorations' and do it all themselves .. chrome does this)

window managers often include a file manager, panel (bar with apps open, or ways to open apps) and a clock, the wallpaper is often done by the window manager. what happens when you click on the empty screen with no apps.. that is handle by the window manager

so no, it is not a windows emulator, tho you can do that with relative ease (and these days have acceptable performance)

'wine' which stands for "wine is not an emulator" .. it actually emulates the service calls of windows.. allowing many games to be played at full speed in linux from windows