On Mac's Preview program, one must surround one's search phrase with quotation marks in order to find an exact string match in a PDF document. But when one fails to surround the search phrase in quotation marks, Preview instead searches for all of the words on a page, and returns results where those words all appear, even if not in the exact order specified.
This functionality is great where one doesn't know the exact phrase. But I have yet to find a program with similar functionality on Windows. So far, I've tried Foxit PDF reader, Adobe Acrobat, Microsoft Edge, and Google Chrome.