Jim used HTML ampersand codes to display the different apostrophes, but they also exist on your computer. Microsoft WORD and many other word-processing programs automatically change the apostrophe and quotation mark keystroke to the appropriate form (or what Microsoft thinks is appropriate). If you copy-paste from a Word or HTML or text document, you'll sometimes get one apostrophe and sometimes the other. If you're over 50, like I am, your eyes are usually too weak to see the difference, and stuff like that can give a guy fits.
-Joe Offer-