My understanding is that they are formulated differently beyond just the sudsing parameter.

Less volume of water is involved so not as much water-softening/treatment ingredients are needed ... but the soil level is proportionately higher regards to cleaning agents and enzymes.

Also components to help avoid color transfer between items due to potential higher concentration of bleeding/dyes in the lower volume of water.

I don't think anybody really knows if it's any different or just marketing hype. Plenty of people use regular detergent in lesser amounts and don't have any problems.

FWIW...in my U. marketing courses in the late sixties local P & G tech/marketing guy came to speak to us. One example he used was laundry and dish detergents. They MADE them suds up because that's how consumers judged the products cleaning ability -- visual evaluation of suds level. Their ads and their competitors ads promoted the characteristic aggressively. By-hand dish-washers and conventional TL-users still do.

Another comparison he used -- valid then, as now -- was automatic dishwashers. Then, as now, dishwasher detergent didn't/doesn't make suds. As you probably know, using conventional detergent in your dishwasher makes quite a mess. HE laundry detergents are kind of like that. "Scrubbing Bubbles" don't get your clothes clean. The rest of the chemistry does.

Learn your water quality and learn the appropriate dosage for your application.

Gwarstong- we were told the same thing in my university Marketing class about the "suds sells" factor, back in the early seventies. Info probably filtered down from the P&G people.