Media Molecule boss Alex Evans has said LittleBigPlanet "as it is" would not work on Xbox 360, mainly because the game had been developed with only one system in mind.
"The 360 is an incredibly capable machine, and you could make a user-generated content game on it, no question - just as you could make one on the PS2 or the Mega Drive, or any platform," Evans told GamesIndustry.biz. "But because we picked our platform, you go and you use every available bit of space, every little processor cycle.
"The design decisions on the PS3 are huge, and I'm sure you realise that having a hard drive on every unit makes a difference. That's another thing - if we didn't have a hard drive on every unit, we'd have to scale back the ambition of what you could save and do.
"So yes, you could make this game on the 360, but it'd be a different game."
Blu-ray capacity, Evans pointed out, also made a difference, with LittleBigPlanet occupying around 40GB because of its tutorial content for players and creators.
Head over to GamesIndustry.biz for part one of the interview with Alex Evans, where he talks about Sony pressure, Peter Molyneux's advice to "go for broke", and explaining the game concept to his mum.
LittleBigPlanet is due out exclusively for PlayStation 3 on 31st October.