Creative Cloud Storage

One cloud storage allocation, but two different (and separate) "users" of that space. One is your photos that are stored in the cloud, the other is a dropbox-style cloud storage, syncing and sharing function (you should see a "Creative Cloud Files" folder in your system's file browser). The latter is also used for storing Photoshop cloud documents, which enables sharing of documents between desktop and iPad systems.

One thing to note, photos synced from LrClassic to the cloud only upload as Smart Previews, which do not count against the cloud storage allocation, wheras photos imported into any of the Lightroom apps are uploaded in full original form, and these of course do count against the storage allocation.