Is there a difference between an a maternal and fetal medicine doctor and an obstetrics & gynecology doctor?

Good question. A maternal fetal medicine doctor is someone who did a fellowship after obgyn residency who specializes in complications and high risk pregnancies and specialized tests like fetal anatomy scans for normal and high risk pregnancies, most mater- fetal med spec do not do the delivery they only help manage your preg, I use them with every one of my preg pts (also they do not do any gyn, like i do).
Yes. A Maternal and Fetal Medicine doctor sees patients that have arise pregnancy with medical disorders like hypertension, Diabetes Mellitus, recurrent pregnancy loss, Lupus etc. Your OBGYn will refer you to one if indicated.
High risk experience. Mfms are high risk pregnancy experts who do three extra years of training after they finish residency in ob/gyn. They learn how to care for un-routine pregnancies, maternal chronic diseases, and babies diagnosed with birth defects during pregnancy.