Do a search as there are a few threads out there comparing FP and IM.
FP - able to do OB/GYN type of things as well as peds plus many procedures.
IM - No peds, OB/GYN, but able to specialize in many fields. Better chance to become a hospitalist. Also does some procedures.
1. Acuity of patients, I think. IM spend more time in the hospital ward. They rotate through more of the IM subspecialties (inpatient, outpatient, consult) and do more time in the ICU/CCU. Continuity clinic is usually 1-2x per week for all 3 years. Those interested in primary care IM typically pick up some non-IM primary care rotations as electives (gyn, ortho, rheum, derm, etc).
FP spend time in the hospital wards and have ICU/CCU coverage as well but typically it is more in the first year or half of the 2nd than the 3rd year. The amount of IM subspecialty exposure depends on the program and the number of electives available, but embedded in most curriculums are surgical exposure (general, ENT, ophtho, ortho, uro). Some programs will tailor each rotation in certain specialties toward the FP orientation, while other programs run the rotation as if you were that specialty's resident. Most programs I've seen have 1st years do more hospital work with more call and less clinic and it flip-flops by the time you're a third year with more clinic time (3-5x/week) with less call and less hospital time.
2. It also differs on the Zebra Safari. Depending on the IM program, there may or may not be an emphasis towards bread-and-butter medicine. Some programs because of the academic/specialty exposure will orient you towards cutting edge diagnosis/treatment and they may challenge you to recognize the zebras. Others will not.
FP typically does not focus too much on the zebras. Most programs want you to focus on the bread-and-butter and nail it down cold. The only catch is that you must know the bread-and-butter over a bigger breadth across all specialties.
Still, medicine is very expansive and both FP and IM will tell you there is too much to know. I think a good program is one where you get sufficient electives where you can pick out your interests/deficits and give you protected time to focus on it.