There is a wide variety of situations. There are programs that pay a stipend of ~$50,000/yr and there are programs that charge over ~$50,000/yr simply for "tuition." So the situations are varied. You can look on the ADEA website for more information about specific programs and tuition/stipends.
A stipend is your "salary." Most hospital-based programs will pay you a stipend as a resident. Sometimes these programs will charge tuition as well, but most of them simply just pay you because they get GME funding from the government. Programs that are within dental school more often than not, charge tuition for their programs and don't usually pay a stipend. Hope this helps....