They mean nothing at all, other than the cosmetic appearance in IB itself.

So, are you saying that the launch storyboard is appearing in portrait orientation (i.e. correctly for a phone held in portrait orientation), but that this is just weird if the phone is actually being held in landscape initially? I have a vague recollection about all iPhone apps starting in portrait orientation, regardless of the actual orientation of the device, then autorotating to landscape if configured to work only in landscape. I suspect it’s “as designed” for the launch screen to appear in portrait in this case.

Surely, the best solution is to have an orientation-neutral launch storyboard? That storyboard isn’t really supposed to show any content. Something bland and neutral may be the best choice.