The Delcro is made entirely from fabric, while traditional velcro straps tend to have the velcro material stitched onto a base canvas or leather material.
Delcro is fully adjustable as the loop surface occupies the entire surface of the strap, while the loop surface of a traditional velcro strap only occupies a small portion of the strap (and is not really adjustable).
The Delcro is also much softer and thinner, and does not have as much structure as traditional velcro straps.