chestermikeuk I read that Pre-iron is completely different to steam in that it heats the drum up, and then you add the clothes to the machine, something to do with the bigger hexagons, the hold heat better, something like that. But I guess it could, as you say, be like Hotpoint's/electrolux's steam where it heats up the steam inside the tub - as opposed to a generator.
Pre-iron I've noticed is only available on the lower range (single line display), the large display models still have steam generators inside and a steam option, instead of pre-iron.