How come my tax return from 2014 is 66 pages, but the one from 2015 is only showing one page?

For Online prior year files, after the year is locked, TTX has stared storing the large-file "All forms and worksheets" PDF (for 2012 and later) so that you can look at all your entries on the worksheets in the coming years This is critical if you have any questions about what you entered into the program should the IRS have a later complaint about your file.  The IRS has been sending out ton's of letters in the past couple months about people's 2014 tax filings....and those folks need those extended PDF files.

For 2015 though, your "Some things you can do" menu shows you two choices...just the bare PDF file for submitting to the tax people is the main choice...but two steps lower on the menu is a download "All Forms and Worksheets" selection that will download the same large file.   Once the Online software shuts down permanently ~15 November, the PDF file that TTX gives you access to will also probably revert to only the larger PDF file.