physically for thee engines, nothing...fuel and engine management varies with sensor and tuning.
you can run E85 in a vehicle not design, but it wont perform as well. it may throw a code until fuel is used and refilled.
research the fuel type and read up, e85 being a higher alcohol percentage, requires more fuel (less MPG per tank), but is much higher octane ( higher performance, if the vehicle can adjust tuning on the fly).
E85 is cleaner fuel as well.