But Apple did a well job, making the user interface suitable for desktop use.
Alike linux such as ubuntu, it has a *nix like file structure.
Most installer packages are in extension .dmg or .pkg.
Or you may install things from source code itself.
There are some way to make repository like installer, alike apt-get or yum in linux.
One of it is macports, macports.org
Installing MacPorts requires XCode to be installed. It can be found on apple website.
XCode with the iOS sdk is pretty huge, total up to 3+Gb.
Mac paths is different from most linux.
The application is mostly installed under /Application.
While the user home directory is under /Users/your_user_name
Other than that, its pretty much the same file structure with linux.
Keyboard wise, its pretty much confusing. There are no direct home or end key.
The function key needs the Fn function to press together to make it work.
But you may change this setting in the System preference, found on the upper left with a small Apple icon.
As for home button, pressing the "Command" + "Left arrow" gives you the home, while "Command" + "Right arrow" gives you the End.
The "Command" key is pretty much alike the control key in windows or linux.
But in terminal, the Control+c of linux have to be "Control"+c in mac.
What is really awesome in MAC is their touch pad. Its multi touch, and it detect 4 fingers!
Using Four finger and dragging down, give the overview of all the tasks in thumbnail.
Using 3 fingers and dragging left gives the "Go back", while dragging right gives the "Go Forward" maneuver. Touching the pad with 2 fingers give the "Right" click trigger. And as usual, using 2 fingers to drag will give the scrolling maneuver, alike the iphone or ipad.
Multi tasking in MAC is pretty much more smoother compared to ubuntu 10.10. But there is a new patch done in the recent kernel hacking which seems to solve this issue on X Windows, and hopefully this will give the more consistant multi-tasking feel on linux.
More on MAC keyboard:
Hope this give you a head start of understand MAC.