So, when Hall and Oates perform at —

No, wait — is it “Hall and Oates” or “Hall & Oates”? You see it both ways depending where you look. If they were a newer musical act, it would be displayed consistently as part of a brand strategy, replete with a logo and corresponding domain name.

Hall and Oates. Hall & Oates. Hall + Oates. Hall x Oates.

Let’s see … Google … Wikipedia … iTunes … Spotify … Oh! hallandoates.com. … Actually, it’s not even consistent there, but the ampersand delineation seems more common, so we’ll roll with that.

So, when Hall & Oates perform at —

No, wait — that’s still not right.

It may seem like splitting hairs, like trying to draw the world’s most unimportant distinction, but it does matter. Because buried in the actual verbiage is a defining characteristic of one of the most commercially successful musical duos of all time. Namely, “We’re actually not a duo, and we never have been,” John Oates said.

“We’re two individuals who work together, and I know I’m parsing it thinly, but that’s the truth. If you look at our albums, from the very first album we ever made, it says, ‘Daryl Hall’ and ‘John Oates’ — it does not say ‘Hall & Oates.’ There’s never been an album that said ‘Hall & Oates’ — ever,” he continued. “The world calls us ‘Hall & Oates’ because it’s easier to lump us together as a duo, or it’s just easier to say, but we did that specifically from the very beginning because we never wanted to be perceived as these two people who are linked together who couldn’t separate.”

So, when Daryl Hall & John Oates perform at Vivint Smart Home Arena in Salt Lake City this Tuesday as part of their co-headlining tour with Train — an evening that will feature a set from Hall & Oates, a set from Train, and a joint set from Hall & Oates and Train (or is it Hall & Oates & Train?) — the night won’t merely highlight a rich, decades-long musical legacy that’s led to inductions in the Rock & Roll Hall of Fame and the Songwriters Hall of Fame, but also a unique and complicated pair of individuals in a unique and complicated musical partnership.

Thing is, Hall and Oates very much appreciate not always having to be Hall & Oates.

(Rob Grabowski | Invision/AP) Daryl Hall performs at the Allstate Arena in Rosemont, Ill., on Monday, May 15, 2017.

“I think the reason we work so well is because we give each other so much space. We’re not a traditional duo — we don’t even sing together that much. What we share is our experiences, and that’s what kept us together, what we have in common, obviously,” Hall said. “… We give each other a lot of space. We’re very separate people.”

Indeed. For one thing, the two musicians spoke with The Tribune in separate phone calls arranged by separate publicists.

Each went on at length about the different hobbies that occupy their time. Hall, whose family “moved to Pennsylvania at the turn of the 18th century” and whose family’s residences are “open-to-the-public kind of houses,” grew up with a love of antique architecture and dabbles in restoration — that is, when he’s not too busy with his VH1/MTV Live/MTV Classic “Live From Daryl’s House” series, in which he and a guest musician talk music and jam … at his house. Oates, meanwhile, did a solo tour to start the year, will do another solo tour later this year, and, as a self-described “powder hound” who lived in Vail, Colo., for “20 or 25 years,” inquired of the quality and frequency of Utah’s most recent winter storm season.

And each was as keen to discuss his latest solo project as Hall & Oates’ latest tour. Oates issued an Americana album called “Arkansas” in February, which he described as “the most focused, pure thing I’ve ever done.” And Hall has a “soul-gospel thing … a very heartfelt and personal kind of grouping of songs,” that will be out end of this year or early next.

(Rick Scuteri | Invision/AP) John Oates performs at Gila River Arena in Glendale, Ariz., on Monday, July 17, 2017, in Glendale.

“We always intended to have separate lives — separate personal lives and creative lives,” Oates said. “That’s one of the reasons we’re probably still able to play together. Because without that, there’s no way we’d be playing together. The freedom of being individuals and the freedom of allowing each of us to express ourselves individually has been part of our musical and personal strategy from the very beginning.”

Fair enough. It was telling, though, that in detailing their separate and individual albums, Hall said he was “moving more and more toward my roots,” while Oates noted he was “trying to tap back into the earliest days of the things that made me want to be a musician.”

What’s kept them together is what they have in common, remember?

These days, that includes a shared acknowledgment that their ability to do arena tours 40-plus years after their formation is, in part, because, as Hall put it, “a whole new generation, [or even] more than one new generation now, has discovered us outside of our initial audience that we had way back when.”

Each also had established a prior relationship with Train singer Pat Monahan — Hall via “Live From Daryl’s House,” and Oates through a performance on a Caribbean cruise ship — and so each agreed to the proposed tour with Train without a second’s hesitation.

Hall & Oates even collaborated with Train on a new single — “Philly Forget Me Not” — to promote the tour, though it’s unlikely the un-duo will ever make another full album of new songs together.

“Oh, I don’t think so. I can’t see why we would. There’s no reason to. We don’t even get to play [most of] the songs we wrote!” Oates said. “… In a way, you have a professional responsibility — people are coming to a show, they want to hear the songs they want to hear. We always include deeper tracks in our shows just because we want to, but there’s no way we could even touch on a fuller list of over 400 songs that we’ve written and recorded. So there’s no reason to do that.”

“The songs are the reason that myself and Daryl and Hall & Oates, we’re still around. We’re still viable and people still wanna hear us because of the songs,” Oates said. “… Now that time has passed, I think people have greater appreciation for what we were able to accomplish. If everyone could write No. 1 hit records one right after another, they would do it. It’s not easy to do.”