What is the difference between and in RSS?

Question

I have the feeling, in every RSS.xml file, both the pubDate and the lastBuildDate match.

I am sure that this one, is not always true...

So firstly, what is

Answer 1

lastBuildDate specifies the last date/time the entry was modified. pubDate specifies the actual publication date/time.

The reason you see these as generally the same is because by the time you get the RSS feed, there hasn't been any edit to the article.

I can't find the RSS spec on this unfortunately, but I am pretty positive that's what they are.