I think it also depends on where you practice. In more suburban areas where there is a glut of physicians (peds/OBgyn) an FP is more likely to do strictly adult medicine. Most people would rather see a pediatrician or an OB for those needs if available, though an FP may be equally capable. Where you want to live could dictate the need for a true Family Practice or an adult medicine practice, where an internist would be best suited.
The one notable specialty for FP is sports medicine. Compared to a wide variety for IM. Also, hospitalists can be either FP or IM certified as far as I know.
Anyone got any other major differences?
lar