Originally Posted by macropod

Most likely, you've changed more than just the Office version. A change in printer drivers (e.g. because you're using a different printer) will also affect the layout, because Word uses information from the active driver to optimise the page.

On Word 2016, justification is also handled differently from Word 2010.

Another possibility, is that the document was saved with the 'automatically update document styles' parameter set and it's now getting different Style definitions from Word 2016.