That is actually a great question. The most obvious is that with residential you will have an individual policy and bill for each property. A residential policy is also overall pretty basic. You typically have the following coverage items and maybe a few added endorsement items.
Dwelling coverage, Replacement cost (determined by a replacement cost calculator), Small amount of personal property coverage, Loss of Rents, Premises Liability (max 1 million), Med Pay, Landlord Personal Injury Liability. Possibly sewer and drain endorsement, service line interruption endorsement ect.
With a commercial policy you can have all of your properties on one policy and one bill. If you are purchasing a BOP you will have far more built in coverages. A BOP is a business owners policy and therefore adds many additional business types of coverage.
You can also look into a commercial portfolio policy, which is like bundling all of your residential policies into one flexible policy that can be customized per each property. One great advantage is the pricing is not calculated the same way as residential policies. A Portfolio policies allow all of the following to be done,
Agreed Replacement Cost(you decide on dwelling coverage amount not a calculator) Multiple People, LLC's, Trusts, IRA's all on one policy, Add Properties in Multiple States, Allows Multiple Lenders, different Loss Settlement Types ie Replacement cost or Actual Cash Value, different coverage type per property ie Vacant Policy or Occupied Policy
Reach out for more information and hopefully some other agents will jump in with their opinions