So for a young woman looking to shift millions of units without completely selling out, the bad girl persona must seem pretty tempting. After all, you get to look like one of the girls, but with an edge that suggests a more grown-up attitude. We’re in an age where Britney and Beyonce are the Heathers of pop music, ruling the “TRL” school with abs of steel and the will to match, luring in all the boys with teasing, never-fulfilled come-ons while embracing their female devotees with withering put-downs of the opposite sex. It’s a formula so devious, you’ve gotta wonder if some record exec didn’t go down to the crossroads and sell his soul to get it. And with two such bad girls dropping albums this week-new teen queen Willa Ford and R&B diva Aaliyah-it’s a perfect opportunity to explore this phenomenon.

Willa Ford is a native Floridian, so it’s logical to assume that she was either a) a Mousketeer or b) a product of Lou Pearlman’s teenpop factory. She’s neither. The closest Willa (nee Amanda Williford) got to the oversized mouse ears that Britney Spears and Christina Aguilera once wore with pride was when Entertainment Revue, the Tampa-based children’s group she performed with, would do shows at Disney World. In fact until earlier this year, Willa’s biggest claim to fame was opening for the Backstreet Boys and her three-year romance with the band’s Nick Carter, which, when it ended, resulted in an avalanche of angry letter and hate sites on the Web generated by Carter’s barely pubescent fans. So Amanda Williford hit the studio, wrote a bunch of songs, enlisted a grip of state-of-the-art producers and emerged as Willa Ford, a self-described “girl playa” and “the female Eminem.” Bad girl, indeed.

By coming out this deep in the girlpop cycle, Willa invites comparisons to her peers that aren’t always favorable. She doesn’t have Christina’s chops. She can’t dance as well as J.Lo. Her songs aren’t as well written as Destiny’s Child’s. And her first video isn’t as compelling as Britney’s MTV debut. Even worse, Willa’s album may be coming out just as teenpop is in decline. Recently, the formerly unsinkable ‘N Sync’s single “Pop” peaked at only No. 19 on the charts. Nevertheless, “Willa Ford Was Here” is pure pop pleasure, an album so craftily derivative that it manages to sound brand new even as you tick off the mandatory elements. Jittery hip-hop beats? Check. Soaring strings and slashing guitars? Yep. Sassy call-and-response lyrics? Totally. Anthemic chorus? Um-hmm.

What makes it all work is the rock-ish, I-just-don’t-give-a-damn sneer that underpins Willa’s delivery. In her hands, generic songs like “I Wanna Be Bad” (sample lyric: “I wanna be bad/You make that feel so good/I’m losing all my cool/I’m about to break the rules/I wanna be bad”), “Prince Charming” and “Tired” hint at the fierce, incantatory power of Michael Jackson’s rock-oriented pop tunes like “Beat It,” “Smooth Criminal” and “Speed Demon.” The beats may be eager to please, but Willa isn’t; there’s a welcome absence of ingratiation to her singing that mars the work of her better-known peers. In fact, Willa makes one think of none other than Michael’s little sister, Janet. Remember, Miss Jackson couldn’t sing like Whitney, couldn’t dance like her brother and didn’t have songs as compelling as Madonna’s. Yet she forced her way to the top with a Nietzschean will to power and a pair of producers who have enabled her to keep going into her third decade. Even after you buy it, “Willa Ford Was Here” may not be the first choice to go in your CD player, but once it’s in there, you’ll have a hard time taking it out.

That said, Willa could definitely take some lessons from the woman behind another of this week’s releases. Aaliyah’s bad-girl imprimatur comes from her scandalous marriage at the tender age of 15 to singer-Svengali R. Kelly, who produced her album. The marriage was quickly annulled, but it guaranteed her a lifetime membership in the Bad Girl Club. Fortunately, Aaliyah is the real deal-a real talent with a real voice and who, even as a youngster, had the ability to sing about grown-up love as though she’d already experienced it. And after leaving one genius behind-her ex was a true R&B traditionalist-she segued to hip-hop avant-gardist Timbaland and his partner in crime Missy Elliott without missing a beat, resulting in a string of hit singles (“Hot Like Fire,” “One In A Million,” “Are You That Somebody” and “Try Again”) that rocked the charts and turned out clubs from coast to coast. And even though it’s been five years since her last full-length album, Aaliyah is here to show bad girls just how it’s done.

Like a 21st-century Sade, Aaliyah and her posse of producers dare to keep almost the entire album in midtempo, with the occasional detour into slow jam territory. There are virtually no uptempo tracks here. Instead, “Aaliyah” unfolds with the coiled intensity of a boa constrictor, wrapping you in layers of dense grooves, tense stutter-step beats and well-chosen accents until you can barely breathe. Then there’s that voice: honeyed, unforced, easy like Sunday morning yet impossible to shake off. Resistance is futile. On the first single, the Timbaland-produced “We Need a Resolution,” Aaliyah croons “Am I supposed to change/Are you supposed to change/Who should be hurt?/Who should be blamed?” until it becomes a hypnotic voodoo trance, while “U Got the Nerve” seethes with anger and disdain. There’s also a serious Spanish influence here; “More Than A Woman” hums with the sexy swing of salsa, and “Read Between the Lines” enlists horns, drums, bells and shakers in a tense merengue-inflected confection. And, in a departure for contemporary R&B, there’s even a pair of absolute rockers-“I Can Be” and “What If”-anchored by the jackhammer insistence of double-time jungle beats.

The album sometimes walks a fine line between being lush and overproduced, but each element is so carefully chosen that it seems almost churlish to say so; this is state-of-the-art hip-hop at its most strikingly original. What’s truly frightening is the ease with which Aaliyah outdoes her pop peers. Britney would kill to sing this well. Christina dreams of this kind of voice control. Sample-happy Mariah would die for beats this original. And while Aaliyah may not pen a single lyric like the fiercely ambitious Willa, she’s a muse who inspires her (mostly male) writers to come up with songs that capture her while preserving a certain mystery. None of the songs on “Aaliyah” will become a female anthem like, say, Lauryn Hill’s “Ex-Factor.” But, then again, what exactly did Sade mean when she sang “You give me the sweetest taboo/That’s why I’m in love with you.” When Aaliyah delivers lines like “Do you wanna roll with me?/We can go to foreign lands/You can hold my hands/Do you wanna ride with me?/We could be like Bonnie and Clyde/Stick by your side,” what they lack in memoirlike specificity leaves enough space for you to imagine yourself inside them. And others, like “Speak your heart/Don’t bite your tongue/Don’t get it twisted/Don’t misuse it/What’s your problem/Let’s resolve it/We can solve it/What’s the process?” reach for a maturity that most girlpop doesn’t even attempt. Sometimes, the baddest thing a bad girl can do is grow up into the woman she was meant to be.