swa66 - 10:42 pm on Feb 26, 2013 (gmt 0)
Your guess is actually quite right.
In HTML, you are supposed to (exceptions aside) to encode any & as & . SO in a <a href=""> or so your encoding works as the rbowser knows it's reading html and will decode the & to & and then use it.
In your address bar: there's no html, so no decoding of htmlentities.