this may vary by school and instructor, but here was my experience with block 3 at glendale.
ob and peds are pretty much all of ob and peds. ob focused on problems in labor and delivery. peds focused on alterations in nursing care due to age, childhood communicable diseases, genetic disorders, abuse/neglect/etc.
med surg was:
GI: peritonitis, perforation, GI bleed, cirrhosis, liver failure, pancreatitis, hepatitis
ENDO: all diabetic emergencies(DKA, HHNS, etc), SIADH, DI, cushings, addisons, pheochromocytoma
URINARY: advanced F&E imbalances, chronic renal failure, peritoneal and hemo dialysis
we have a mentoring program that matches us up with students in the block above us. it's great for things like this, because they always pass on their syllabus so we know what to expect.