I found out differently. The online version only saves a PDF of your tax return, which cannot be used as a file type to upload to a download version of TurboTax. PDFs are essentially "read-only". It is rumoured that the online version can save a copy of your return as a tax-data file, but it is not offered as an option.
The consequence of not saving my tax return as a data file means that were I to use the download version for a subsequent tax year, I cannot transfer all my personal information.
If you buy the download version, you can save your tax return in both file types: PDF and data file.
You might wonder why I switched to online last year (2020 tax; Calendar year 2021)? I was in between computers so had no personal storage device. Neither does TurboTax because it doesn't archive my data.
I wish 2 bad choices made a right, but they don't.
