I've been doing more of a deep dive into this. Qelbree doesn't seem like it's solely an NRI like Strattera despite being marketed as such and many of the effects are not only due to NET inhibition for which Qelbree is a moderate inhibitor of (vs Strattera that is a highly potent NET inhibitor). The biggest difference is in the serotonin effects of Qelbree over Strattera, which means it may be helping with mood and anxiety much more.
In the PFC, it increases levels of NE > DA > 5HT (but not glutamate, histamine, gaba, or acetylcholine). In the nucleus accumbens, it increases 5-HT > NE > DA.
Viloxazine was historically described as a norepinephrine reuptake inhibitor (NRI). Since NRIs have previously demonstrated efficacy in attention deficit/hyperactivity disorder (ADHD), viloxazine underwent contemporary investigation in the treatment ...
www.ncbi.nlm.nih.gov
The open label long-term extension adult data by Nasser show that Qelbree continues to decrease ADHD symptoms at each time point they measured up to one year at 400mg and at doses of 500-600mg, it separates out from 400mg.
Strattera has cardiovascular contraindications and warnings, which include sudden death, stroke, MI that Qelbree doesn't have. The QTc prolongation doesn't happen with Qelbree even at supratherapeutic doses. For Strattera, the QTc prolongation happens in 1.2% after 4 years of treatment.