they are different because if they defrag the same way, there will be copyright lawsuits
That is really about it. different companies gotta do things differently unless they purchase a license.
personally it let windows do it automatically. its been years since I done any manual defragging.
Curious why Piriform Defraggler, Auslogics defrag and the built-in Win 7 defragmenter all show different levels of fragmentation? Is the built-in Win 7 adequate? Piriform is so thorough it takes forever to complete (I've never let it run to completion), Auslogics is full of PUPs (found by malwarebytes), and Win 7 only shows 1% fragmentation! Thanks for helping me understand and suggesting which to use.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic