Absolute Path gives the whole path to where the file can be found on the hard drive
e.g. C:\hello\world\program.exe
Relative Path is where the file you want is found in comparison to the program that is wanting it
e.g. a html file in C:\hello\world\index.html wants to execute that program.exe so instead of stating the whole path (the absolute path) he just writes in \program.exe meaning the file needed is in the same directory as the html file.
Owe and everything Glide said was right