What is the difference between complementary medicine and integrative medicine?

Integrative Medicine. Integrative medicine is healing-oriented medicine that takes account of the whole person, including all aspects of lifestyle. It emphasizes the therapeutic relationship between practitioner and patient, is informed by evidence, and makes use of all appropriate therapies. These other therapies may be "complementary" or "alternative" in nature, but can be blended in treating the person.
Semantics. Complementary implies "in addition to" conventional med; integrative is a seamless blend of both.
Very similar. Complementary medicine generally means using techniques which "complement" or help while using standard Western medicine treatment. For example, treatment of pain with acupuncture. Integrative medicine is a bit broader in recommending use of the best science supported natural remedies & lifestyle for longer term health while using the best of mainstream Western medicine to get you out of trouble.