Strange Apostrophe from Copy and Paste in PHP

Tried to Google this but couldn't find it.  A friend wanted to try and edit one of my PHP pages so he wouldn't have to keep bothering me with small changes.  Since it was just the content of a string used for the body of an email, I figured why not.  He made his changes and I uploaded the file to the dev server.  Once I tested it, I realized PayPal was no longer processing on the page and returning an error.  He swore he only changed a few words in one string.  After looking closer, I saw the issue and fixed it. But what I don't understand is the why.  Here's the code as he sent it over and the issue is the apostrophe in the word member's:

<li>Confirm that payment is listed in the member’s payment info.</li>

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And here's an image of part of that code:

In the circled part of the image, his apostrophe is on the left and the one I type in my editor is on the left.  Definitely two different apostrophes.  Just need to know how he typed that because I haven't been able to replicated it.  Thanks.