Osteopathy and chiropractic started out as distinct healing professions in the late 1800s in the USA. Andrew Still, a physician and surgeon 'discovered' osteopathy in 1872 when he became dissatisfied with conventional medicine. He believed the bone 'osteon' was the starting point for pathological conditions. D.D Palmer was the founder of chiropractic in 1895. Palmer may have been a student of Andrew Still for a short time.
Palmer proposed that spinal manipulation influenced the nervous system whereas osteopaths believed that manipulation had an effect on the body’s circulation. Scientific understanding of physiology was very limited at the time.
Chiropractors and osteopaths treat mainly muscular and skeletal problems. Chiropractors often use manipulation, particularly of the spine as part of their treatment. This is sometimes referred to as an adjustment. To better understand what this is, you may like to read this post. Osteopaths may also manipulate their patients but more frequently use mobilisation. Both professions use various other soft tissue techniques as part of their treatment.
Chiropractic and osteopathic manipulation and mobilisation are recommended by the National Institute for Health and Care Excellence (NICE) for the treatment of back pain. I have observed osteopaths treating patients and can see a time when there are much closer ties between the two professions. In the UK chiropractors are regulated by the General Chiropractic Council and osteopaths by the General Osteopathic Council. When deciding whether to consult a chiropractor or an osteopath you may find it most helpful to seek out a personal recommendation from family members or friends. Hope this helps.