Klone is right....it is about the model of care (midwifery vs medical). Midwives believe birth is a normal process, not a condition that always requires hospitalization or intervention. Midwives have more training in attending normal, low-intervention births. OBs are trained in specialized areas such as surgery, most don't see many natural births during their training either.
Midwives "catch" babies. OBs "deliver" babies. :)
I highly suggest that you take the opportunity to shadow both types of professionals to really "see" (feel) the difference.