Your first example is usually called a "relative URL", meaning that it is resolved by your browser at the time you click on the link relative to whatever directory/folder the browser (or search engine) is currently looking at. Relative URLs can be duplicated across many folders in a large Website but all resolve to different actual pages. Relative URLs can be very troublesome, especially if they are encoded in multiple partial formats.
Your second example is usually called an "absolute URL" (although technically it's "an absolute, fully resolved URL"). Every URL has to be fully-resolved before it can be used to fetch content. The chief difference between RELATIVE and ABSOLUTE URLs is that with relative URLs the browser (or search engine) figures out how to fully resolve the link and with absolute URLs the resolution is provided by the Web content.
I have recommended that people use absolute, fully resolved URLs for many, many years as there is no real "safe" way to ensure that relative URLs will always take the visitor to the correct destination.
Edited by Michael Martinez, 02 April 2013 - 12:50 AM.