It’s about how the manufacturer issues the engine control package and tuning of the engine. This is common in many industries. You will read many posts about how people get much more power from their basic rated engine such as the L2501
More Fuel=More Power! They set the injection pump differently for each model. As far as Ads, use an Ad Blocker to stop most and you can also become a lifetime member which gets rid of the ads
They do not have "the exact same engine". At a minimum the engine management components are different. Something as simple as different fuel maps and different boost levels can easily get you an additional 7 HP.