Medicare is a government plan for people age 65 or disabled after 2 years on disability. Original Medicare has Part A (free is if you worked 40 quarters/or can collect on your spouses) and Part B which has a monthly premium paid to the government.
They combined Part A, B & D of Medicare with copays. Usually, they don’t have premium but you have copays for services. All companies have a network so you must make sure your doctor accepts these plans. Some companies offer money back on Part B. They also include other benefits such as silver sneakers, vision and hearing which original Medicare doesn’t.
Part A is hospital which has a deductible and Part B is for outpatient also has a yearly deductible. After deductible Medicare pays 80%. You have your freedom because there is no network if providers accept Medicare. This is where you would consider a supplement/gap plan to cover the remaining 20%.
Part D is the Rx portion of Medicare. They say its optional but if you don’t get it when eligible then Medicare will penalize you back when you were. I say take the cheapest one because you will end up paying it in the end.