Are there any differences, feature-wise, between Firefox for Mac and Firefox for Windows? I know that Chrome for Windows and Chrome for Mac are extremely similar. So similar that I only notice one difference for the Mac version: the green + button doesn't maximize. However, that can be remedied: http://maximizechrome.com. According to Google - I'm not sure where - there's only one difference: dragging highlighted text. I didn't notice this, but I don't usually drag highlighted text.

I don't use Firefox very often, but one thing I do appreciate is when an app behaves the same no matter your OS. I might even switch to Firefox if it does this. Thus, the question: Are there any differences, feature-wise, between Firefox for Mac and Firefox for Windows?

I mean real differences, not just things like the dropdown box styling provided by the OS.
There is a significant issue in viewing PDFs on web sites.

Adobe Reader for Mac has a browser plug-in for viewing PDF files. It's never been compatible with FireFox for Mac, or Safari 5.1 and higher for Mac.

With FireFox on Mac, there's no reliable way to view a PDF file that's on a link from a Web site within FireFox itself. The best you can do is download it and open it using a PDF viewer on your Mac.

With Safari, you can view a PDF file in the browser window with Mac OS X's built-in PDF display capability. It works well enough, but it isn't the Adobe Reader Browser Plug-in, and that can create some problems with services that depend on the Adobe plug-in.