They’re basically saying they won’t ship off data to be processed to anyone else. Apple server hardware will process it in data centers.

There’s then a further promise that this hardware will be isolated from other things apple is doing, so that no other apple processes not related to AI will be able to see this data.

So, for instance, some other AI company might cut a deal with Amazon, get a discount on AWS processing, and in exchange, let amazon snoop through the data being processed. Or, a company might use a cheaper process in an existing data center that isnt particularly secure, and just not care if its being spied on. I’m sure there’s more likely scenarios as well, I’m not a security expert, but apple is promising to thwart any similar thing, by promising the “cloud” for AI is a unique cloud, not just encrypted or whatever, but actually physically separate from everything else

Its the equivalent of saying “this product won’t trigger your peanut allergy, we’ve built a facility that will never see a peanut, so cleaning procedures are easy and accidental contamination is impossible since this product is the only thing made in this factory.”

These are still just claims though, not facts, so we’ll see.