NEW YORK — Evening newscasts on ABC and CBS are both gaining ground on market leader Brian Williams of NBC News, but that’s one of the few things they have in common.

Behind Diane Sawyer, second-place ABC is making strides with a sleek “World News” that emphasizes the American family, news that hits home and the cultural zeitgeist. Scott Pelley has revealed himself to be a traditionalist at “CBS Evening News,” leading a show weighty with significant national and international events.

NBC’s “Nightly News” remains in first place, where it has generally been since the late 1990s except for a brief run by Charles Gibson at ABC. The Nielsen company said NBC’s viewership is down from last year while ABC and CBS are up, with ABC in July winning a week among the key 25-to-54-year-old demographic for the first time since 2008.

Despite decades-long prophecies of doom, network evening newscasts remain a vital part of television’s landscape, collectively reaching more than 22 million people each weeknight. Often, Williams’ newscast is more popular than NBC’s prime-time programming.

Now there’s a creative push to distinguish broadcasts that once seemed interchangeable.

“We recognize the environment has changed very significantly,” said James Goldston, ABC’s senior vice president of news. “The days when an evening newscast can act as a digest of the day’s news are gone.”

What’s happening in the evening is similar to the morning, in terms of content. ABC’s “Good Morning America” has swept past NBC’s “Today” with a breezy show on the tip of pop culture and hosts that ooze chemistry. CBS remains in third, but has gained ground since it stopped trying to imitate its rivals.

The most visible recent sign of the different approaches came not in the evening but a few hours before. On July 22, when Britain’s Prince William and Kate Middleton became parents for the first time, ABC cut away from regular afternoon programming for more than an hour to talk about the birth, coverage that featured Barbara Walters.

CBS didn’t bother with a special report, a judgment that stood out more because NBC did the same as ABC. Pelley reported the story on the evening news.

CBS News President David Rhodes quipped that “it wasn’t the Second Coming.”

“We tried to not completely lose our minds covering it,” Rhodes said. “I don’t think we were making a statement. I think the others were making a statement about themselves by doing it.”

Goldston is fine with that. ABC has stayed on the story, airing a “World News” report last Wednesday featuring Prince William talking about being a new dad.

“Millions and millions of people in America were interested in the birth of the royal baby,” he said. “It’s news. We just report the news.”

Day-to-day, the differences are more muted. In 13 of 23 weekdays in July, the two evening newscasts led with the same story, according to news consultant Andrew Tyndall. On some of the days they diverged, ABC picked stories with more populist appeal. One day, ABC led with weather and forest fires, while CBS started with Egyptian politics. ABC led another day when the women kept imprisoned in a Cleveland home released a video message; CBS had a follow-up report on the San Francisco plane crash.

Getting beyond the day’s obvious headlines is where different priorities emerge.

ABC frequently airs detailed reports by Paula Faris that give concrete advice on how families can find savings; she recently talked about trimming fees included in home sales and costs related to sending someone off to college.

“At the end of the broadcast, people not only feel empowered, smarter and enlightened, they know some of the things going on in the world that are interesting, that people are talking about,” said Michael Corn, “World News” executive producer.

At CBS, “we like to have news all the way through the broadcast,” said Patricia Shevlin, executive producer.