Very similar. But different.
PocketLists.com cloud works and syncs the Pocket Lists app data similar to how iCloud works for all the basic iOS apps (you just sign up, and the rest is done automatically). But technically both clouds are independent and not connected with each other.
We've created our own syncing cloud because it was the best (and the only) way to provide rich syncing & collaboration experience for Pocket Lists.
If we would choose iCloud for being the primary way to sync the data for Pocket Lists, then we would be limited by personal sync & backup only. All other powerful features — including collaboration, list sharing, and teamwork — would not be possible.