This is a subset of the issue of semantics vs formatting. A definition list says what they are, a list of related key/value attributes, but does not say how to display it. A table says more about layout and how to display the data then what the data inside is. It limits how the list can be formatted both by overspecifying the format and by underspecifying what it is.
HTML, historically, has mixed up semantics with formatting. Font tags and tables being the worst examples. The move to CSS for the formatting and the stripping of a lot of the pure formatting tags out of XHTML restores, somewhat, the separation of meaning from formatting. By separating formatting into CSS you can display the same HTML in many different ways reformatting it for a wide browser, a small mobile browser, printing, plain text, etc...
For enlightenment, visit the CSS Zen Garden.