I read an article last year sometime (I think it was the Journal of Internal Medicine or something like that) describing a consensus they had reached describing what professionalism was. It's basically a job that follows a certain set of codes or ethics. For medicine these contained four, if I remember correctly -- patient primacy, patient autonomy, social justice, and one more I'm forgetting.
I think "profession" connotes something specific, though, and it's been traditionally used to describe only a small subset of jobs, including medicine, law, and education, that require a strict code of ethics.
Anyway, sorry for being so vague -- I read this in passing and don't remember all of the details.