"Scars" are what you can see outside the body, while "adhesion" is what we generally refer to as scars inside the body.  Both are essentially the same thing- thickening of the connective tissue that occurs as part of the healing response.  

Depending on the type of scar, its location, age, and associated symptoms, different techniques may be used to treat them.  Here are two examples:

John Barnes Myofascial Release is a gentle technique used to treat the fascia, which is the connective tissue that forms the building blocks of our bodies and connects us from head to toe.  This includes treatment of restrictions that occur due to scars/adhesions.  It is an integral component in both the treatment of physical impairments as well as in maintaining flexibility, mobility, and a balanced body.

Microcurrent Point Stimulation Therapy combines cutting edge medical technology with the wisdom and philosophy of Acupuncture, involving musculoskeletal and neuromuscular aspects of the body.  Through specific application of direct current microcurrent to trigger points, acupuncture points, and scars, pain can be dramatically improved and scars can be released.