I'll try to answer this simply. I am an RN and proud to be a nurse.
Things we have in common are that we both go into it wanting to help people from a healthcare perspective. But how we go about that is different, although we work cooperatively.
In other words, our professional perpectives focus on different things. Both things that help people from a health perspective.
These things are defined by our education and license to practice.
My definition of Medical Doctor will be shorter because I'm far more familiar with the definition of a nurse (and any medical doctors are welcome to chime in here - I did look around and this was the best I could do right now; big issue is to just show the inherent differences, not say one is better than the other, etc).
Now, obviously, the actualities of medical and nursing practice are FAR MORE complex and overlapping than what is listed here.
BUT,
at the most basic level, the a doctor is educated and licensed to treat the person's illness and the nurse is educated and licensed to treat the person's response to their illness.
Most nurses go into nursing wanting to be a nurse because it's a worthwhile profession that helps people manage their health issues. They recognize their role and work within the perspectives and guidelines of nursing. If a nurse goes into nursing to be a "mini doctor", he or she will probably be pretty disappointed because the nursing perspective is different. Over the years I've trained a lot of nurses and it's been rare that I've had to say, "that is not your role". Nurses know their roles (although in certain areas, those lines may get a little blurred as the team works so closely together). And of course, advanced practice nurses such as Nurse Practitioners do take on some of the characteristics of medicine, although generally they never lose their perspective as a nurse (which is a great asset and why patients often enjoy them).
Nurses who want to be doctors go to medical school. My pediatrician started out as a nurse. Not surprised whatsoever as the first day I met her I didn't even know her (she was covering for my own pediatrician) yet she had an incredible bedside manner and gave me a hug when I became upset about something. I remember thinking if we ever needed to switch, I'd want her! And that's exactly what happened. We have a great working relationship because she understands how I think and I know she understands things from a "response to" perspective, even before she became a parent herself.
I could go on but I'll end here. I think you get the jist.
I work with great doctors and great nurses and am amazed every day at the work we do TOGETHER on behalf of our patients.
The last thing I want to say (and I'll put my flame suit on) is that, although there's controversy within the profession itself and this pathway was driven by the nursing shortage after WWII and the women's movement of the 50's and 60's, most professional nursing organizations feel that, with the complex needs of patients today, the entry to professional nursing practice should be at the bachelor's level (BSN), not the associate's. Some hospitals, such as my own, will only hire nurses who have a bachelor's degree or higher, and in fact many staff nurses have degrees at the master's level or above. The reason for this is that studies have shown that morbidity and mortality rates are lower for hospitals that employ mostly BSN nurses. Although people may disagree, this isn't really disputable. So yes, the bedside nurse you have in some hospitals may have almost as much education, training and experience as your doctor does. "2 years vs 8 yrs" can be very misleading.