The difference here is in the reported legal structure of the agreements. SDS is a joint venture that operates on a distribution model, and the Sony/Lionsgate agreement is also a distribution agreement. Disney/Sony was specifically reported by Deadline to be a licensing arrangement. It’s a...
You’re describing a distribution model. Under a licensing model, it’s more likely that Sony would need to ask for permission to release a UHD of Poor Things, and Disney would then have the right to decide whether to grant permission and on what terms. The latter arrangement is more consistent...
Nobody here knows because no one has read the agreement, and the reporting on it has been sketchy on the contract details. Deadline reported that it was a licensing arrangement, which (usually) give the licensee more control than a distributor does under a distribution agreement, but the devil...