The first thing most people learn about Tegan Quin is that she is exactly one half of folk-pop duo Tegan and Sara. The second thing, usually shortly thereafter, is that Sara is her identical twin sister. But while 27-year-old Tegan may be biologically similar to Sara, musically she is anything but.

The Canadian sisters, who crept into the scene almost a decade ago with a set of self-produced demos, initially dropped in the midst of a younger, edgier slew of Lilith Fair acts, copping both Alanis Morissette's grrl-rage and Ani DiFranco's witty wordplay; they actually nabbed a few spots on Sarah McLachlan's womanly Woodstock incarnation in 1999. But the duo's second and third records, 2002's "If It Was You" and 2004's "So Jealous," allowed Tegan and Sara to break out as a folkie force to be dealt with in the already crowded world of indie rock.

And nowhere did the differences between Tegan and Sara become more obvious than the recording of last year's "The Con," the duo's most successful effort to date.

"Sara spends a lot more time on her songs. For some tracks, she'd clock herself demoing and recording it for more than 60 hours. For me, the most I ever spent working on a song was eight hours," Tegan said in a recent phone interview. "But then, for the record, Sara wrote around 10 songs, and I wrote about 30 -- I write a ton more so I write a lot quicker."

It's not just the quantity of tunes, but the quality as well that separates these two. While Tegan's songs on "The Con" tend to flow per usual for a pop song ("Verse-chorus-verse-chorus-bridge-chorus-done, for the most part"), Sara's often twist and turn unexpectedly, resisting any sort of structure altogether. The difference in structure makes sense, considering what each sister chooses to reveal in song.

"I don't like to talk about what's actually happening in my life; it's more just about pure emotion, which makes people feel that my songs are more sing-along. They can relate them to themselves," she said. "Sara's songs, on the other hand, paint this dramatic picture of her life. They're very specific. They induce a lot of intense staring from the crowd."

And the differences extend beyond artistic creation. Whereas Sara is often the first on the tour bus to discover new bands (she introduced their crew to Arcade Fire long before that band broke out), Tegan is comfortable with her old standbys like Robyn and Against Me!, "screaming along in my bunk and still being 14 years old."

Still, for "The Con," the Quin sisters came together like few bands can. The record's 14 tracks have enough hummable hooks to last the possible three years until the next disc drops, each balancing somewhere between jumpy indie pop and lonely singer-songwriter fare. The tunes feel fleshed out, with layered and looping guitars and percussion (and the occasional power chord punch) filling every corner of the room, all tied together by the twins' masterful harmonizing and laser-sharp vocal timbre. The music aches terribly one moment, then gets sick of loneliness and resorts to sarcastic wit the next. And somehow, the whole thing, easily their best work, is really fun.

"I cringe at some earlier work because, well, we had bad hair -- true. I'm not crazy about the production -- true. But really, it's because I don't hear us naturally. With 'The Con,' it's not us with drum and bass layered on top. We're totally there. We're not peaking out -- we're in charge," she said. "We recorded everything, in sequence, for over a month before even adding drum and bass. Even the other musicians [including AFI's Hunter Burgan and Weezer's Matt Sharp] are following our ideas, not just playing on top of us."

Still, Tegan does long for some individuality; it's hard always being lumped into a band where her personal quirks rarely see the light of day.

"There are moments when it's frustrating being half a person. That's what Tegan and Sara feels like at times. Half the set list will be mine. Half the interview questions will be mine," she said.

And hesitating just a bit, she added, "Sometimes I just want them all."