What are the differences between nurse pracitioners and physician assistants?

I wanted to be an Ob/Gyn but went into journalism in undergrad. The urge to work in women's health is still there. What are some career options.

A nurse practitioner is a registered nurse who has completed advanced nursing education (generally a master's degree) and training in the diagnosis and management of common medical conditions, including chronic illnesses.
Nurse practitioners provide a broad range of health care services. While nurse practitioners are not trained in medicine, their advanced education in nursing makes this a fast-growing midlevel profession.

Nurse Practitioners (NPs) provide much of the same basic, non-emergent care provided by physicians (generally of the type that is easily treated and not life threatening) and usually maintain collaborative working relationships with physicians. NPs are licensed by the state in which they practice, and have a board certification (often through ANCC - American Nurses Credentialing Center) in their area of practice. Rather than a generic focus of education, Nurse Practitioners are able to specialize in an area of study they desire (e.g. Pediatrics, Family Practice, Adult, Geriatric, etc.), and provide care within the scope of their expertise.

Physician Assistants (PAs) are non-physician clinicians licensed to practice medicine with a physician's supervision. Unlike nurse practitioners, who are trained in advanced nursing, PAs receive education specifically in the practice of medicine. In many states, PAs are state-certified and work under the auspices of the physician's license. Physician Assistants generally have a master's degree in medicine from an accredited university. They have the option, depending on the state in which they practice, of being nationally certified or not.


**** I got all this info from Wikipedia. There is more info on Wikipedia about the careers and the growth of these professions.*******