Intro is a part of a news, which is an introduction to the news. It is placed before the beginning sentence/paragraph or lead. It contains less elements of 5W1H. Intro is explaining what the news is about briefly. It commonly located below the headline.
Lead is a beginning sentence/paragraph of a news and it generally contains more elements of 5W1H. As lead has more elements of 5W1H, it is actually more details than intro. Lead is explaining more about what is going to be talking in a news. It can be located below the intro.
The example:
Intro:
The president-elect, who will be sworn into office in 57 days, said he was "pleased" the formal presidential transition has begun.
Lead:
President-elect Joe Biden introduced key members of his Cabinet and national security team during an event in Wilmington, Delaware, Tuesday afternoon, and declared: "America is back."
https://www.nbcnews.com/politics/2020-election/biden-hold-event-national-security-team-n1248770