The files with the large number of pages included all the worksheets and other things that were used by TurboTax to prepare your returns. Only a few pages each year are actually included in the tax return that is sent to the IRS. The 12 pages may be the actual forms that are sent to the IRS. There will be a file with a similar amount of pages as in the past that includes all the worksheets.
When you save your return, there are several choices of what you can save from just the return as filed to the return with all the worksheets.