Neither software gives you real world results.
ATTO uses highly compressible data to test Read/Write speeds.
Think of ATTO as "best-case" scenario.
An example of highly compressible data that I can think of is a Microsoft Word document.
Nobody works with only
notes and memos.
AS-SSD uses highly incompressible data to test Read/Write speeds.
Think of AS-SSD as "worst-case" scenario.
An example of an incompressible file is a .wav music file or a .mpeg video file.
Unless you're a music producer or video producer, nobody works with only
those types of files.
Real world data usage is in between the two.