I've got a hot webquestion for all you webmisters and webmistresses out there:

At some point <b> and <i> were replaced with <strong> and <em>. I gather the reason for this was to convey important semantic information.

So I ask you this, are these two forms semantically equivalent?

<em><strong>butts</strong></em>

and

<strong><em>butts</em></strong>