Both would qualify as you having been covered by health
insurance.
You would answer "I had health insurance coverage all
year." under the Health Insurance tab in the program and continue through
the interview.
You should answer "Yes" on the screen that asks "Were you covered by any of these plans in 2017?".
You will click the button next to "Affordable Care Act,
aka: Obamacare" on the screen that asks "What type of plan were you
enrolled in?"
You will enter the information from your 1095-A, which is
the form you should have received from the Marketplace.
The TurboTax software will reconcile any tax credit you
received or are eligible for.
The program will know that the months not reported on the
1095-A were months you had other coverage (Medicare) because you answered that
you had coverage for the entire year.
See the attached screen shots for more clarity on entering the information.