Isaac Harari writes:
I have a personal photo library of approximately 200 GB which is now in iCloud and I can access with all my devices. The problem is that I also have another work photo library that sometimes I like to have on my iPhone. How can I keep both libraries in iCloud but keep them perfectly separate?
Unfortunately, there’s no option to switch among collections or libraries in iCloud. For any given device or computer, you’re pairing iCloud Photo Library with an iCloud account. You could create separate iCloud accounts for different libraries and maintain different OS X accounts to switch among them. But since there’s no similar facility in iOS, it would be a huge mess to swap iCloud accounts to show a different library there.