Copy Attributes vs Make Links - What's the difference?

What’s the difference between Copy Attributes and Make Links?



I can see that there are some differences in the items listed in those menus.
But the Modifiers one seems to do the same thing in both, for example and I was wondering if it is actually doing the same thing. I have heard both methods described as a means of giving multiple objects the same Modifier stack.
Now I realize I really don’t understand what’s happening in these menus on the datablock level and got curious.

Would anyone be willing to give a brief explanation?
Thanks

Yes, you are right. Linking is copying except whatever changes you make to one IN EDIT MODE (and other
circumstances such as materials), it will take effect on the other.
Copying is the object is copied just for that moment.

You can read this: http://wiki.blender.org/index.php/Doc:2.4/Manual/Modeling/Objects/Duplication