This is pretty widespread technology - BMW's ISG, modern scooters stop their engine at lights, a spanish company called Valero developed a system of their own. It's usually called a "microhybrid" because "mild" is a little too generous.
GM had the nerve to call its full-sized pickups "hybrids" with this technology when the Prius became popular.
As for the differences, my guess is that they want to distinguish their efforts by making "fuel economy" version of their cars. Any business's practices (however odd) pretty much boil down to one issue: making money. Fuel economy sells now.
- LostCause