The TurboTax online editions are only for tax year 2017.
The software purchased from Amazon to be installed on your personal computer for a prior tax year is the same software that is available on the TurboTax website here - https://turbotax.intuit.com/personal-taxes/past-years-products/
Note - If you purchase the TurboTax Deluxe edition from Amazon and are needing to also complete a state tax return that the Deluxe edition comes in two versions, one with and one without the state program.