'Unfinished' size is the size block/strip we start with, 'finished' is the size that you see when your project is complete.
If you start with 2.5 inch strip and make a 4 patch, the patches will be 2 inches when finished in your project.
Most patterns tell you to cut the 'unfinished' size.
Good luck! I love my wonder cut ruler---saves lots of time!