How to achieve this scatter effect using Illustrator or photoshop?
I have tried using scatter brushes in Illustrator but it is not exactly the same thing. Please help!
You can do this in Photoshop with custom brush you need to define (rectangle shape) and then play with the settings (remember that "roundness" in this case will be thickness of the shape. This is what you could get.
Using Direct Select Tool you can move single rectangles co you can add more random effect. The main advantage of illustrator is that you can add single rectangles to make the scatter look more random.