The pop stars nominated at this year's Grammy Awards couldn't be more different from one another, both visually and sonically. In the two biggest pop categories, Best Pop Vocal Album and Best Pop Solo Performance, every spectrum of pop is represented: from soulful to candy-colored and everything in between.

As the Grammy Awards approach, MTV News will break down the contenders in both categories. So, here we go.

Best Pop Vocal Album
Adele's 21 has six nominations under its belt at this year's show, including the biggie, Album of the Year. Since its release nearly a year ago, Adele's heartbreak opus reigned on radio, the charts and the collective hearts of the lovelorn everywhere. It boasts production from Ryan Tedder, Paul Epworth and Rick Rubin, and tracks the singer's heartbreak after a split from a former beau.

Cee Lo Green gave the world a big "F--- You" with his The Lady Killer, which dropped in November 2010, and the album has sustained its momentum thanks to that one track (and Cee Lo's "The Voice" gig). The album got some songwriting and production help from fellow nominee, Bruno Mars, and in addition to this nod, its track "Fool for You" is also up for some gold.

Lady Gaga's love-yourself album, Born This Way, is a metal-disco composition about romance, New York City and couture. With production from RedOne, Fernando Garibay and DJ White Shadow, the album was released last May, and while the sound looked to the future, it also paid homage to her past when she enlisted the late Clarence Clemons from Bruce Springsteen's E Street Band and Brian May of Queen. Bruno Mars crooned his way to the top of the charts with his debut album Doo-Wops & Hooligans. Displaying his love for melodies and lyrics about love and loss, Mars' experiment in mixing doo-wop and new millennium production value managed to make him a household name and a big-time nominee.

Album of the Year-nominated Loud was Rihanna's return to form. After a dark turn on Rated R, Ri was feeling sunnier, saucier and sassier on the 2010 album that featured production from Stargate and Tricky Stewart and tracks like the fist-pumping "Only Girl (In The World)" and the reggae-influenced "Man Down."

Best Pop Solo Performance
On "Someone Like You," Adele's big voice and knack for heartache was on full display. The second 21 single got a songwriting and production assist from Semisonic frontman Dan Wilson (the guy who gave us "Closing Time" in the '90s) and follows Adele as she comes to terms with the loss of her former flame.

Like Adele, Bruno Mars put his heart and soul on the line on the Doo-Wops & Hooligans uber-ballad, "Grenade." The song, produced by the Mars-fronted the Smeezingtons, tracks a distraught man as he realizes the woman he loves doesn't feel the same way about him.

Lady Gaga had been teasing "You and I" for some time, but before the finished version appeared on Born This Way, no one could have guessed what May, Gaga and super producer Mutt Lange could have cooked up. What they released was a funky, smashing ode to reclaiming lost love.

Katy Perry hadn't touched on deeper issues on earlier singles, but when it came to her Teenage Dream feel-good anthem, "Firework," she went there and it took on a life of its own. With Ester Dean and Stargate working with Perry on the song, it topped the charts and became the fourth in a record-breaking string of #1 hits off that album.

Like Perry, Pink gave a voice to the disenfranchised on "F---in' Perfect" (off her greatest hits collection that dropped in 2010). Working with Max Martin and Shellback on the track, she hit the top of the charts and empowered her fans thanks lyrics like, "You're f---ing perfect to me."

Chaos! Profanity! Wardrobe malfunctions! Don't miss our Grammy red-carpet live stream this Sunday, February 12, for a full three hours of mayhem, starting at 5 p.m. ET on MTV.com. And the fun doesn't end Sunday: MTV News has you covered for all the Grammy red-carpet fashion, Grammy winners and Grammy news until the hangover wears off!