The version of the Ambiguity page which I'd really like you to see uses JavaScript to make my life a bit easier. Unfortunately, there have been a few revisions of JavaScript, and different browsers implement different revisions of it. Some cool features which I'd like to use are only available in JavaScript 1.1 and later. This is implemented by Netscape Navigator 3 and later, and Microsoft Internet Explorer 4 and later. Navigator 2 and Internet Explorer 3 implement JavaScript 1.0, and trying to do the page with that proved too difficult. So I wrote a version which doesn't use JavaScript at all. Instead it has 47 little HTML files, one for each picture... (Well, actually, that page, like most of the others on this site, uses a bit of JavaScript to display the Last Update, so I don't have to keep remembering to change it. But that's JavaScript 1.0. And I didn't create the 47 HTML files by hand. Instead I created one and wrote a Perl script to copy it 46 times, making appropriate substitutions throughout.)
Having done that, I thought it would at least be nice of me to send you to the right version of the page automatically, rather than expecting you to work it out for yourself. So when you click on the main Ambiguity link, you're actually running a little bit of JavaScript that figures out which version of the language your browser supports and sends you to the right page.
However... what if your browser is really old, or is one of the "non-mainstream" ones, and so doesn't implement JavaScript at all? When you click on the main Ambiguity link, your browser won't know what to do with it, and so won't do anything. (You probably won't even see an error message, because browsers are designed on the assumption that HTML will change and expand, and so they ignore anything that they don't recognise.) That's what the alternative Ambiguity link is for. It's a "traditional" link to the non-JavaScript version of the page.
There is another way that the main Ambiguity link could fail to do anything. Browsers which implement JavaScript allow you to turn it off, mainly because of security concerns. If this applies to you, it's best to use the alternative link; you aren't actually missing much. Whoever turned JavaScript off in your browser probably did it for a good reason.
If you really want to turn JavaScript on, in Navigator (version 4, anyway), select the Edit menu, and then Preferences, Advanced, and put a tick next to "Enable JavaScript." This takes effect immediately, although you'll need to reload the page. In Internet Explorer (version 3, at least), select the View menu, and then Options. Select the Security tab, and put a tick next to "Run ActiveX scripts." In typical Microsoft fashion, you have to quit Internet Explorer and restart it for this to take effect.
Note on the name "JavaScript": JavaScript is not to be confused with Java, although it has some things in common with it - primarily the uncomfortable C-like syntax. It was invented by Netscape, and its main purpose is to add a bit of life and interactivity to static web pages. The name appears to have been a marketing decision; it was originally going to be called LiveScript. So far I've used it mainly as a labour-saving device. I'm not really doing anything with it that I couldn't do by some other means. You could conceivably write a "wander-round-the-maze-picking-up-objects" type of game in it, but it'd take a lot of thought and planning.