Semantically the two are not really interchangeable. Other than being lists.
The dl element represents an association list consisting of zero or more name-value groups (a description list). A name-value group consists of one or more names (dt elements) followed by one or more values (dd elements), ignoring any nodes other than dt and dd elements. Within a single dl element, there should not be more than one dt element for each name.
Looking at the spec for more usage examples might help give a better understanding of the element(s).
For normal websites, I’m not really sure how useful they are, but I can imagine for more document heavy sites they might be.
I guess you can use it for Opening hours. It seems a bit unnecessary, but I don’t think it would be semantically incorrect.
<dl>
<dt>Open:</dt>
<dd>Monday</dd>
<dd>Tuesday</dd>
<dd>Wednesday</dd>
<dd>Thursday</dd>
<dd>Friday</dd>
<dt>Closed:</dt>
<dd>Saturday</dd>
<dd>Sunday</dd>
</dl>