What's the trivial difference between the 15" and 17" versions of the MacBook Pro?

Solution 1:

In the left corner of the top menu, pick the apple menu and select About This Mac.

In the About This Mac panel, click the More Info button. if you hover your mouse on Hardware you can see the general info about your macbook pro such 15" or 17".

As Dori said in comment above solution for before 2007 now choose Graphics/Displays from the left column, it does display the screen resolution.

Solution 2:

If it's the unibody MacBook Pro, I believe the 15" has an SD card slot, and the 17" has an ExpressCard/34 slot. Also, the 15" only has two USB ports, whereas the 17" has three.

Solution 3:

Might not be that Trivial, but the size between the side of the computer and the keyboard is larger in a 17’’ model:

MacBook Pro 15’’:

15'' http://www.sunsetmac.com/images/6615244.gif

MacBook Pro 17’’:

If the user fails to find the information as described above, you can tell him to count the number of holes (no measure required!) ;)

Solution 4:

Max screen resolution in Displays preferences.