While there's probably some overlap for certain use cases, I'd say they're more complementary. In fact, Restic leverages rclone to support a lot of cloud storage services. Restic is specifically meant as a backup tool and does encryption, deduplication, snapshots, and now apparently compression. Rclone is more of a synchronization tool/copying tool (which could also be used to make backups), more like rsync or even just cp (but with cloud storage support).

Rclone is more for syncing than backups. Its great for moving files between storage systems and syncing one path to a destination. Some backup tools use it for uploading/etc.

Rclone is like rsync for the cloud, you can sync files to a google drive or other service. And like CCC it can archive deleted files as a saftey net. I love the simplicity, no deltas, snapshots or restore procedures, the files are just there on the destination.