Unless you've got a pre-teen daughter at home, chances are you can't tell the difference between the Backstreet Boys and 'N Sync. Come to think of it, it's not so easy to keep these prepackaged musical groups apart even with a youngster around who's constantly singing along to their latest hits. As it turns out, the members of the two prevailing boy bands themselves are now caught up in something of a musical identity crisis. Only this one is likely to be played out in courtrooms and lawyers' offices rather than on concert stages and in recording studios. Think of it as a fierce struggle among reigning princes of modern-day bubble gum music. And into the mix add a not-so-invisible power behind the throne who's responsible for the very existence of both bands and has a major financial stake in their ongoing success.

The brouhaha started last month when the five-member 'N Sync decided to part company with RCA Records, which is owned by Bertelsmann AG's BMG Entertainment. The group then turned around and signed a reported $12 million deal with Jive, part of Zomba Recording Corp. That struck a decidedly sour note with the five guys from the Backstreet Boys, who already record on the Jive label. Seems that the Backstreet'ers view the two acts as being just a little too similar and doubt that the label can adequately promote both bands. Needless to say, some big -- as in huge -- numbers are at stake in this legal battle of the bands. The Backstreet Boys' debut album sold 8.6 million copies, while its second CD, "Millennium," has already sold 6.2 million copies since its May release. For its part, 'N Sync has sold nearly 7 million copies of its first album, released last year, with plans to release its sophomore disc in January. Louis Pearlman, a Florida-based pop music entrepreneur who essentially created and molded both groups, stands to lose big if 'N Sync starts recording for a new label.

It was Pearlman's company, Trans Continental Records, that clinched a five-album deal for 'N Sync with RCA. Earlier this month, Trans Continental, joined by BMG and RCA, filed a $150 million breach-of-contract lawsuit in New York state court and federal court in Orlando against 'N Sync, Jive and Zomba. Along with seeking damages, Pearlman is also demanding that 'N Sync stop performing under that name -- guess who owns the trademark? -- and return master recordings that have already been produced for the group's second album. "We're going to shut them down," says J. Cheney Mason, an Orlando attorney who represents Trans Continental and vows nothing less than a "scorched earth policy" against 'N Sync. The objective, he says, is "no tours, performances, rehearsals or recordings" by the group for any company other than Pearlman's. Mason reserves most of his criticism for "some lawyer who comes in and wants to get something from a contract that he didn't have a goddamn thing to do with in the first place."

Just the other day, the band informed Pearlman's company it had retained the services of Helene Freeman, an entertainment litigator at New York's Dorsey & Whitney. While Freeman declines to talk about the case, a publicist for 'N Sync calls Trans Con's dealings with the group "the most glaring, overt and callous example of artist exploitation that the music industry has seen in a long time." Entertainment lawyers who have been watching the skirmishing from the sidelines for the most part tend to be skeptical of efforts to break existing contracts. "Like teen-agers, they feel it's not fair," quips Alan Rader, of O'Melveny & Myers, referring generally to musicians who try to break free from their labels. "So they go out and find a lawyer who doesn't blush easily.... Lawyers convince their clients that they have a constitutional right to renegotiate [a recording contract]. There isn't one that I know of." But there sure are risks to getting into a legal tussle with a record company. "People don't like to hear that some rich, snotty brats are suing to make even more money," says Todd Allen, of Century City's Rutter Hobbs & Davidoff, who has represented major record labels and bands in contract disputes.

For starters, virtually no one buying a group's latest album cares what label it's on, says Allen. And if the label succeeds in preventing a group from ditching it for another, "it can charge back all its litigation costs to the artist." Meanwhile, the Backstreet Boys are making their own legal noises about leaving Jive now that 'N Sync wants in. The group's attorney, John Branca, of Century City's Ziffren, Brittenham, Branca & Fischer, fired off a letter earlier this month to Jive, saying the band wants out of its contract. The group has also added to its legal chorus by bringing in Hollywood litigator Marty Singer, of Lavely & Singer. Currently in the midst of a 53-city tour that sold out within an hour, the Backstreet Boys flexed some legal muscle last year, settling a royalties lawsuit against Trans Continental and then renegotiating its contract with the company.