Soul music has long ceased being the exclusive province of African Americans, a pure expression from a society that literary critic LeRoi Jones once called "blues people." These days, soul music is whatever you want it to be: the slickly produced pop of Justin Timberlake and Christina Aguilera, the pillowy ballads of Robin Thicke, even the electronic visions of Jamie Lidell and Junior Boys.

It doesn't matter anymore if you're black or white, but you still have to sing the blues. Even if it only evokes Delta hoochie coochie and Motown funk in spirit, raw vocals, emotionally direct storytelling, and even a little melisma should underline the music.

Blessed with a sweet and husky voice and an ability to ride a backbeat with flourish, Joss Stone is a powerhouse singer. Four years ago, she was a British teenager lucky enough to have Betty Wright, the early-'70s soul icon behind hits such as "Clean Up Woman," as a producer on her debut, The Soul Sessions. At the time, she seemed like a less threatening incarnation of Macy Gray, providing a little edge amidst the Norah Joneses on adult contemporary radio.

Stone has already established herself as a star, so it's odd that her latest album, Introducing Joss Stone, is drawing unfavorable comparisons to another UK soul singer, Amy Winehouse. Winehouse, it seems, is everything Stone is not: honest and lonely, while Stone is confident and loved (at least in song); ragged and disheveled, while Stone is beautifully composed and ready for her multimedia moment.

Ironically, Winehouse's second album, Back to Black, is carefully premeditated. It presents Winehouse amidst '60s-inspired décor produced by Mark Ronson and Salaam Remi, and the duo's rarified, boozy music evokes Portishead's artfully crumbling soundtracks. Winehouse responds to Ronson and Remi's backdrops with an anguished performance worthy of Naomi Watts in Mulholland Dr.; she never breaks out of her role as the ugly duckling done wrong.

That single-minded focus makes Back to Black both problematic and compelling. You never get the sense that Winehouse is being too personal: Her chemical dependencies (from a love of "puff" and drink that may require "Rehab"), her perfunctory shout-outs to Donny Hathaway and her constant moaning over boys who make her "Wake Up Alone" all feed into the character she portrays. But she plays it well, and there's a sense of drama and sexual tension to her songs—particularly the aforementioned "Rehab" and "Just Friends"—that's noticeably lacking in Stone's music.

Stone can sing circles around Winehouse, who tends to stick to the same vocal range. On Introducing Joss Stone, she blows and blows and blows. She slams every lyric harder than a hockey puck, overshadowing the tasteful, complementary production of Raphael Saddiq. Tracks like "Arms of My Baby" are mere vehicles for Stone's vocal gymnastics.

If Winehouse's artful Back to Black evokes the soft-focus sorrow of Laura Nyro and Joni Mitchell, then Stone follows the forceful, over-the-top showmanship of Patti LaBelle. If only she had a song as good as LaBelle's "Feels Like Another One" (or even "If You Only Knew"). A few tracks from Introducing—the symphonic "Bad Habit" and the funk workout "Tell Me 'Bout It"—stand out. But she could exercise a little more subtlety; even promising numbers like "Headturner" end up sounding overstuffed.

Introducing's numbers aren't particularly memorable. Meanwhile, Back to Black is full of great songs. On the "You Know I'm No Good," Winehouse sings a line—"I cheated myself/Like I knew I would"—in such an indelible way that it seems to reverberate on permanent loop, like a not unpleasant memory.

Soul fans are like anybody else: They want records that sound unique and innovative, and artists who possess a sense of mystery and enigma. Winehouse's "heartbroken" aura may be just a mask—in reality, she often turns up at events with her longtime fiancé. Regardless of the facts surrounding her life, the emotions in her music ring true.

Perhaps the only thing Winehouse and Stone have in common is their skin color and British backgrounds. While Winehouse aims for a discerning, hipster audience, Stone is being marketed toward the SUV moms and American Idol watchers. Introducing sounds bland and predictable to some, and bright and energetic to others.

Certainly, the two singers could learn from each other. With a little sunshine and lyrical variety, Back to Black wouldn't sound so oppressively tough. And if Stone made songs that encompassed her imagination instead of a corporate blueprint for adult contemporary, then Introducing Joss Stone would truly show her soul.recommended