There are so many articles written about Functional medicine. Here is a quick overview, how Functional medicine is different.

Patient-oriented care. Disease-oriented care.
Focuses on the root cause(s). Focuses on the symptoms.
Long-term solutions. Temporary fix of problems.
Individual treatments based on biochemistry, social factors and genetics. Everyone get the same treatment.
Holistic approach means addresses the whole person and recognizes the interaction between different organs and systems. For example, connection between digestive issues and skin. Addresses isolated set of symptoms and organs where every specialist treats their special organ (gastroenterologist –digestive issues, dermatologist –skin conditions, etc). No connection between single organs and symptoms seen
Oriented on chronic illness like diabetes, heart disease, cancer, mental illness, and autoimmune disorders like rheumatoid arthritis & Hashimoto thyroiditis. Oriented on acute care, diagnosing and treating trauma or short term illnesses, such as a heart attack, infection, or broken arm.
Prescribes combinations of nutraceuticals, botanicals, therapeutic diets, detoxification programs, and/or stress-management techniques. Prescribes pharmaceutical drugs with plenty of side-effects.
Focuses on changing lifestyle and nutrition in the first line. Drug-centered approach, „pill for every ill”.
Spends a lot of time with patients, listening to their histories and looking at the interactions among genetic, environmental, and lifestyle factors that can influence long-term health and contribute to complex, chronic disease. Spends 5 to 15 min with patient in average.
Healing as goal of treatment /healing in perspective. Chronic conditions cannot be treated, patients take pharmaceutical drugs for the rest of the life(hypertension, diabetes, arthritis, etc).