What is the difference between absolute and relative?

Answer 1

absolute will likely start with http://www. it's web page address is absolutely correct without ambiguities. a relative address could start with a slash or just the name like demopg.htm and if the site was moved to another server, this file might or might not be there. with the relative addresses, the file will be there(hopefully if nobody deleted them lol). both have there place in programming it site.

Answer 2

in more general terms, an absolute path include the root directory, a relative path is a path relative to the current directory.
exemple :
/home/user/images/myImg.jpg is an absolute path
If the working directory is /home/user/images/ then myImg.jpg is a relative path.