Macworld reader PJ wrote in to ask about disabling My Photo Stream and iCloud Photo Sharing without losing anything. He received dire warnings when he attempted to turn them off. In most cases, you won’t lose anything, but tread wisely.
First, let's go over the three different methods Apple has for sharing and syncing photos. It’s common for Macworld readers to get confused about how the many methods interact—especially in making sure that you retain images (and videos) if you disable a service. The three methods are:
My Photo Stream. My Photo Stream lets you push all the photos you take across your linked devices to all your linked devices, including Apple TV. It’s photos only (not even Live Photos!), not video, and images persist 30 days.