Why do some files display the magnifying glass  and others the download arrow ? From what I see they are both using the same html code:

<a class="instructure_file_link instructure_scribd_file" title="fs_midterm.pdf" href="/courses/68569/files/21023485/download?wrap=1">

<a class="instructure_file_link instructure_scribd_file" title="Key Equations.pdf" href="/courses/7980/files/16680801/download?wrap=1">