Once squeaky clean and baby-faced teen stars, Justin Bieber and One Direction have quickly discovered the harsh realities of living in the public eye.

The young artists each released albums Friday that -- while partly staying true to pop formulas that have made them rich -- also lay bare their struggles at discovering adulthood at the height of their fame.

"My life is a movie and everyone's watching," the 21-year-old Bieber intones near the beginning of his new album, "Purpose."

"Life's not easy / I'm not made out of steel / Don't forget that I'm human / Don't forget that I'm real," he sings.

The Canadian singer demonstrates his quest for maturity not just lyrically but musically on "Purpose," his first album of original work in three and a half years.

Bieber on several tracks -- including the album's early hits "What Do You Mean?" and "Sorry" -- plays with a mellow, downtempo tropical house beat, moving away from his typical pop-R&B sound that had done little to distinguish him from other mainstream pop stars.

- Beset by personal woes -

Bieber, who owes his new sound to LA-based electronic producers Skrillex and Diplo, has banked on "Purpose" to rehabilitate his star power after becoming better known for his off-stage antics than his music since he put out his last album, "Believe," in 2012.
Among his most infamous non-musical moments, Bieber was caught racing a Lamborghini in Miami Beach while under the influence and without a license.

A judge ordered him to undergo anger management courses for throwing eggs at his neighbor's home in a glitzy section of Los Angeles, while in Argentina another judge dropped a bid to arrest Bieber for allegedly assaulting a photographer.

On "Sorry," Bieber offers an apology of sorts. But his regrets appear directed not so much to the world at large but -- many fans presume -- to ex-girlfriend Selena Gomez, a fellow former teen star and singer.

Bieber teams up with yet another teen sensation turned adult, Ariana Grande, on an acoustic version of "What Do You Mean?" Other collaborators on "Purpose" include rappers Big Sean and Nas as well as Halsey, the 21-year-old electropop singer whose career has seen a meteoric rise.

"Purpose" is not entirely absorbed by introspection. Bieber's breathy track "Children" consists of unlikely, if unspecific, social activism as he sings, "What about the children? Look at all the children we can change."
And Bieber's reflective tone does not necessarily mean he has changed his ways. He recently ended a concert in Norway after one song, apparently upset over fans throwing water, and walked out of a live interview in Spain.

But in an interview with Britain's New Musical Express, Bieber argued that he had been held to a different standard than other teen stars and said of his life now, "I'm struggling just to get through the days."

- One Direction rocks out -

Bieber will follow his album with an extensive tour of North American arenas starting in March in Seattle.

While Bieber is marking a return, albums have become a ritual for One Direction each holiday shopping season. The English boy band has released an album without fail every November since 2011 after they became famous through talent show "The X Factor."

Yet One Direction's new album, "Made in the A.M.," marks the band's first without founding member Zayn Malik, whose departure in March prompted surprisingly bitter exchanges among the lads reputed for affability.
The band insists that it is not splitting up, but says it will go on an undetermined hiatus after "Made in the A.M.," which followed marathon touring that ended October 31 in Sheffield.

For their perhaps final album, the young men who had become so synonymous with light pop decided to rock out.

The song "Temporary Fix" is driven by guitars with a touch of the verve of alternative rockers such as The Killers. "Olivia" offers a Beatles-esque melody, while One Direction on several tracks sounds more like Coldplay or mid-career U2 than a boy band.

One Direction mostly sticks to gooey love songs but at times the lyricism also seems wistful about the band's stint of glory.

On "Love You Goodbye," Liam Payne sings, "It's inevitable that everything that's good comes to an end."