What's the difference between managed care and medicare?

Restrictions. Essentially when you "give up" your tradionalmedicare and opt into a manged care plan you are trading "restictions" for money. So, you may not have to worry about paying a deductible in a managed care plan but now you are restricted to the insurance netwwork panel of doctors. You may have to get referrals before being allowed to see certain doctors, and authorizations before procedures.