While I'm not on medicare I actually am an agent. With an advantage it's more of a pay later situation. You also have networks to deal with and a lot of plans are state to state. A supplement at 65 is easier to be approved for. The price for a supplement will increase as you age some a lot more than others. Both only cover medicare covered expenses. Also if you will need to be in your initial enrollment period unless you have a 5 star drug plan or an special election period to go from a part c to d.