How would the functionality and implementation compare with Atlas Hive hook for example https://atlas.apache.org/1.2.0/Hook-Hive.html ?

Give a concrete hive hook example, it will be Atlas Hive Hook. It's a direct comparison of Spline. Atlas Hive Hook and Spline work similarly when we look at them from a user's angle. We deploy a jar file, run your normal spark job or hive task, we expect the lineage information (and more) spit out. I have implemented both Spline and Atlas Hive Hook for our internal use. Basically, I convert Spline and Atlas Hive Hook's output into Datahub's so we can have lineage information automatically.