OMM = Osteopathic Manipulative Medicine
OMT = Osteopathic Manipulative Treatment/Therapy
They are synonymous.
Yes, I have seen it first hand. Hard to explain as I have not started medical school yet. There are several techniques within OMM/OMT.... As far as I know from reading books and other references, the purpose is to maximize the innate quality of the body to heal by helping the body position it's veins, nerves, arteries, etc. for maximum performance and flow.
May I suggest you read Osteopathic Medicine: A Reformation in Progress.
The authors summarizes some of the osteopathic techniques and help you understand the philosophies and history a bit more.
Some of the Osteopathic Techniques these author's mention:
- Soft Tissue and Lymphatic Treatments
- High Velocity, Low Amplitude Thrust
- Articulatory Techniques
- Muscle Energy
- Counterstrain Technique
- Myofacial Release
- Craniosacral, Cranial, OCF (Osteopathy in the Cranial Field)
- Visceral Techniques
"Osteopathic manipulative treatment (OMT) maybe used as a primary means of treatment for a problem that appears to be of a nonsevere, musculoskeletal origin, or as adjunctive therapy along with medication or surgery - again, to enchance homeostatic recovery and adaptability," (p49)
Hope that gives you some idea.