Very few apps are considered Digital therapeutics (DTx). The Digital Therapeutics Alliance - for which we are clinical advisors - wrote an in-depth definition, which you may find here.
Digital therapies are distinguished by the fact that they are software used for therapeutics and/or medical use. They are therefore regulated according to their risk for patients and have completed studies to validate their effectiveness.
From a regulatory perspective, DHTs that claim to prevent, control and treat a health condition (but also diagnose such a condition) are subject to the control policies of regulatory agencies such as the US Food and Drug Administration (FDA), Health Canada and the European Commission (EMA).
This is not the case for health and wellness apps. These do not need to be regulated. To understand the difference between the two (DTx vs Health apps), please read this article.