La Rationale Est..
As the detergent markets on both sides of the pond move towards mainly liquid and or gel products, one thing is normally missing; bleach.
Most if not all European detergent powders for whites and colourfast laundry contain oxygen bleach. However few liquid or gel products, if any do, hence these stain release products which are mainly oxygen bleach (the powders are activated oxygen bleach, same as found in detergents).
On this side of the pond, IIRC, none of the Tide liquid detergents contain any sort of oxygen bleaching agent, however their number one detergent powder, Tide with Bleach, and a few others, contains activated oxygen bleaching systems.
Enzymes are another component of these "stain release" products and they compensate for the fact again, many liquid/gel detergents do not contain enzymes (non-bio).
Haven't tried the Ariel Excel Gel that arrived eariler this week, but per the bottle the product does not contain bleach, but does have enzymes.