Saving a document as a PDF is recommended for distributing to others because PDF files, in general, are rendered the same way across all modern Windows computers. Since Windows and OS X each have different native PDF readers and fonts, the PDF file you previewed in Windows may look different when opened on a Mac depending on the way the PDF file was created.

Possible Differences

Some PDF files containing interactive elements such as 3-D graphics and forms will look fine on both the Windows and Mac versions of Adobe Reader but may not display correctly on other PDF reader software. If the PDF file uses a font that isn't installed in OS X and isn't embedded to the PDF file, the PDF file could look different on a Mac regardless of the chosen PDF reader.