According to Consumer Reports, the main differences between original Medicare and Medicare Advantage are:
Snippet of Article: "Original Medicare allows you to use any provider that accepts Medicare reimbursement, while Medicare Advantage plans require you to use a local provider network.
You can't buy a Medigap plan if you have Medicare Advantage, but you can buy one if you have original Medicare. Medigap plans cover all or part of original Medicare's deductibles and co-insurance. ..."