I think The Rehearsal is far more existential and has an interiority that N4U entirely lacks. Especially the later episodes walk this very fine line between genuineness and hilarity/sarcasm that gets to the root of Nathan's inability to come to terms with the fact that he's unable to control all the outcomes of events in the world, often times ending up in a place that he did not foresee coming that he wished he could avoid. His "rehearsals" are almost like a coping mechanism to reconcile with a world of relationships that he wishes he could redo. But they're often quite silly.