From my website - https://www.joelguarna.com/:

Treatment Approaches

Cognitive-Behavioral Therapy
What is Cognitive-Behavioral Therapy (CBT)? The history of CBT dates back to the seminal work of B.F. Skinner, the father of modern behavior therapy. At that time, behavior therapy was a reaction to the traditional Freudian forms of psychotherapy that were only loosely based on scientific principles and were difficult to subject to rigorous scientific study. Skinner held psychology accountable as a science of human behavior, forever changing the face of psychotherapy. Techniques drawn from Skinner's basic behavioral science continue to be employed with good effect in modern psychotherapy. Skinner's account, however, had its limitations. The most notable limitation was that his account of human language and cognition failed to generate a vigorous line of basic research, limiting its evolution to forms that could be employed with patients with complicated psychological problems. Instead, the field opened to the work of Albert Ellis and Aaron T. Beck, the founders of modern cognitive therapy. Ellis and Beck, and their many successors, transformed the practice of psychotherapy by emphasizing therapy techniques that aimed to change the content and manner of one's thinking, not just their overt behavior. Cognitive therapy and behavior therapy continued to cross-fertilize each other over the past several decades. Modern CBT incorporates both cognitive and behavioral techniques. CBT has become the most well-known, mainstream approach to therapy, partly because it has, by far, the strongest research support for its effectiveness in treating a wide range of emotional and behavioral problems. CBT has been found effective in treating depression, anxiety disorders, the effects of trauma, substance abuse and addiction, complications related to medical conditions, and many other conditions.

Acceptance and Commitment Therapy
What is Acceptance and Commitment Therapy (ACT, said as the word "act")? ACT, just approaching its 30th anniversary since its inception, is an innovative form of behavioral and cognitive therapy that has built upon both the strengths and the weaknesses of traditional cognitive-behavioral therapy (CBT). ACT is based on a behavioral account of human language and cognition called Relational Frame Theory (RFT), which has "filled in the holes" left by Skinner's theories. RFT, in contrast to Skinner's accounts, has generated a vigorous body of basic research into human language and cognition, providing fuel for the development of new treatment approaches. The "fruit" of this progress can be found in the philosophy and basic concepts underlying ACT. ACT has moved away from the traditional CBT emphasis on changing or correcting one's thoughts in order to alleviate suffering. Instead, ACT aims to alter the functions of our private experiences (thoughts, feelings, memories, bodily reactions), so they no longer entangle us. Said another way, ACT aims to change our relationship with these private events so we can become free from their grip, and free from the patterns that bind us and prevent us from living a flexible, meaningful, and enjoyable life. In the service of these aims, ACT incorporates acceptance strategies, mindfulness techniques, and a wide range of behavioral approaches already known to be effective from CBT. ACT is one of a family of interventions inside the CBT tradition writ large that are focusing on the person's relationship to experiences rather than on the content of these experiences. The data on ACT and related approaches are moving CBT itself toward a new model that emphasizes being open, centered, mindful and actively pursuing values. Because of that, ACT and CBT as a larger tradition are becoming more difficult to distinguish over time.