The difference between the Radiators and your average neo-hippie jam band is simple: the Radiators have better arrangements, truckloads of better songs, two singers drenched in Southern soul, two guitarists who aren’t scared to get their hands dirty, a pianist who does his Professor Longhair roots proud, the telepathy that comes from two decades on the road, and a deep connection to the natural voodoo of New Orleans. Other than that, no difference at all.

The Crescent City band’s latest bio still drops the names of Phish, Blues Traveler, the Spin Doctors, and Widespread Panic. And you can’t blame the Radiators, who begin a two-night stand this Sunday at the House of Blues, for going after that well-heeled audience. They share some classic-rock consciousness with the above-named bands, though they’re more selective with their influences (the Band, Little Feat, and the early Dead are in their mix; Pink Floyd and the later Dead aren’t). And they operate like many post-Dead bands in that they give their fans reason to trade tapes by knowing hundreds of songs and playing a different show each time out. But as their new Radiators CD (on Rattlesby, their 11th album overall but only their sixth studio disc) attests, these guys know tricks that aren’t taught at any college in Vermont.

Chief among them is capturing that cosmic thing that’s always been in the best New Orleans R&B. And they’ve got a resident expert in keyboardist Ed Volker, who writes most of their original number (singer and co-guitarist Dave Malone supplies the rest). “Deep in My Voodoo,” the Volker/Malone tune that opens the new album, is as close as the Radiators ever get to a straightforward love song, with a gentle tune and hummable chorus. But they know that you can’t settle for gentle and hummable when you’re playing something called “Deep in My Voodoo,” so they set it to a percolating Meters-like groove. The mix of earthy and airy elements is what makes it fly.

“Untouched by Human Hands” is more lowdown, the kind of streetwise R&B number Earl King or Ernie K-Doe might have cut in the ’60s (the riff from Mountain’s “Mississippi Queen” is in there too). But the words are all apocalyptic Southern-gospel imagery. It’s the end of the world as we know it, and they feel funky. There’s nothing gospel about the disc’s third standout, but the greasy “I Wanna Be Your Driver” has one thing in common with the Chuck Berry song of the same name: neither is about cars.

Like fellow New Orleans mainstays the Neville Brothers and Dr. John, the Radiators have had mixed luck in the studio, often coming out with a dampened version of their live sound. Like all their studio albums, The Radiators is song-centered — if you want to hear them jam, pick up 1999’s Live at the Great American Music Hall (High Sierra) or ask any fan for a bootleg tape. But Jim Gaines, who manned Santana’s Supernatural, is the first producer who’s known enough to do the obvious, capturing the sound of their rhythm section instead of turning it low in the mix or (in the case of their late-’80s Epic albums) digitizing it beyond recognition.

“This is going to sound weird, but the reason the album worked is that we had so little time to do it,” notes bassist Reggie Scanlan from his Louisiana home. “For the actual recording process, we had only 14 days. And that didn’t give us time to think about how we should be making a studio album — we had to do a self-edit right away.”

Preferring to work under pressure, he says, is what the Radiators have in common with the jam brigades. “I think we’re more song-oriented than a lot of those bands, but I think that people who like Widespread Panic or moe. would like us. I’d put our stuff in the same genre, but it’s less about jamming than about bands who like to play live and who take chances on stage. Whether that chance is doing an hour and a half of some brooding groove or doing a quick about-face in the rhythm — the thing is that you’re putting yourself in a position where you could really screw up in front of an audience.”

It may seem odd to find the Radiators at the House of Blues this weekend, only a few days before the start of the New Orleans Jazz & Heritage Festival, which is usually one of their busiest weeks. “That’s because we’re on tour all the time,” notes Scanlan, who says he’s playing at least 14 shows, with the Radiators and spinoff bands, during the 10 days of Jazzfest. “It’s going to be an interesting one this year. I was just looking at my schedule and realizing that I have a rehearsal when I’m supposed to be at a gig, and a gig when I’m supposed to be at someone else’s gig.”

Then again, the shared tendency to overwork is one thing that’s kept the band together 20-plus years. “You can’t have a band this long unless you really like playing with each other, and we do. That has to do with keeping a musical conversation going on. And that’s like any relationship — long as you’ve still got stuff to talk about, there’s still a point.”

The Radiators play the House of Blues this Sunday and Monday, April 22 and 23. Call (617) 497-2229.