Mac storage basics · Checking your storage
Do I still need macOS Storage settings if I use a storage app?
Short answer: Storage settings is a good overview, but it can't move data to an external drive or explain sudden space loss. Storage Studio uses the same macOS features and adds those parts.
macOS Storage settings is good for a quick overview and its recommendations are worth using. It doesn't move things to an external drive, explain sudden drops in free space, show folder-by-folder detail across your Library, or release space held by local snapshots.
Storage Studio works alongside it rather than replacing it: it uses the same macOS features where they exist (for example online-only cloud files and local snapshots) and adds the parts macOS leaves out, such as moving big folders and apps to an external drive with a link left behind. See how Storage Studio compares.