I have done extensive tests with PDFs exported from both MsWord for Mac and Pages.
I can see very little difference between the rendering of the MsWord version or the Pages version which is not surprising as they both use the OSX Quartz PDFContent framework to generate the pdfs.
When I examine them in Acrobat Pro, Firefox, Safari, Google Chrome and Preview they all render them differently from the worst (Acrobat Pro) up to the best (Preview), in ascending order of quality.
The fonts are Adobe Truetype OTF versions of Helvetica Neue so Acrobat should be getting it right but isn't.
I suspect on Windows all the PDF rendering is being done by Acrobat, or an Acrobat plug-in. Whether that is written better on the PC or not, I don't know. I also can't tell if it is a Truetype hinting problem. Preview seems to get it right whatever it is doing.
My PC is currently disassembled so I can't generate any Ms Word PC PDF versions of the files to compare. If you care to do that and and email them to me I'll look at those as well.
To isolate a problem it is necessary to compare like with like and narrow the problem down to one factor.
You supplied me with a pdf from the Word for Windows document that uses a completely different font, Times New Roman, instead of the Helvetica Neue used in the Pages version.
Difficult to establish what is going on if I am looking at something else all together.