They both, of course, drive Chevys. And they both currently are top-10 in Cup points.
They also both qualified in the top three for Saturday's Subway Fresh 500 here at Phoenix, with Busch claiming his second career pole and Stewart nabbing the third starting spot.
Oh, and then there's all that love-'em-or-hate-'em, overaggressive driving stuff that leaves them often being showered in boos rather than adoration.
Yes, both of these drivers have their critics, legions of fans who literally curse their names if and when they take the checkers first at any given race.
But there also are distinct differences between the two. Stewart, of course, is a veteran in his 30s who already has two Nextel Cup championships to his credit. Busch, meanwhile, is about two weeks shy of legally being able to drink alcohol.
Stewart has had plenty of time to learn how to handle the criticism, to be able to deflect it. And it's been well documented over the past year or so how he also has figured out how to better enjoy his life as a race car driver – though he seemingly does, at times, suffer relapses.
Stewart even has been able to endear himself to new fans, thanks mainly to the ridiculous hot streak he went on last summer and the memorable fence climbs – especially at Indy – that accompanied his success.
Then there's the relationship with the media. No longer is Stewart shoving photographers, punching reporters and kicking tape recorders. Don't be fooled, he still lets the media have it, but it's an amusing, (usually) good-natured sarcasm rather than a full-blown tirade (though the moderate tirades still can happen every now and then).
Stewart certainly had reason to be jolly and willing to joke around after his strong qualifying run Friday, and it showed in his postrace press conference. He was talking about the run that placed him third on the grid when Greg Biffle, sitting directly to Stewart's right after qualifying second, interrupted and told Stewart he was now fourth on the charts. (Only the top three qualifiers are required to attend postrace media sessions.)
"Really?" Stewart asked before realizing Biffle was kidding. "I'll be honest – I'd be pissed if I came here and didn't have to be here."
Stewart then said he was kidding. Which he probably was – though he again pulled no punches, literally or figuratively, when a reporter asked what Stewart considered to be a "dumb question."
"If we knew half of what you guys ask … we'd be bookies in Vegas making trillions of dollars," he said.
Stewart is at ease, having fun in situations that perhaps in past years would have brought out his darker side.
It's a lesson Kyle Busch continues to learn, and Phoenix is the perfect place for the schooling to continue.
Busch's win here last fall came on the same weekend that his big brother Kurt Busch had a run-in with the police and was benched for the final two races of the season by then-team owner Jack Roush.
In the postrace press conference, Kyle Busch was asked about his brother's situation. He gave an answer suggesting the media had misreported some of the facts and then said he wouldn't answer any more questions about his brother.
But another one came. And it was a perfectly fair question from a reporter wanting Busch to clarify what he said earlier about the media trumping up the Kurt Busch story. Kyle called the question inappropriate, abruptly ended the press conference and left the media center.
Here was a 20-year-old kid who just won a race shortly after his brother was arrested and suspended. It wasn't difficult to understand Busch being emotional, but that doesn't mean the behavior was justified. And he, or someone else on his No. 5 team, realized this, as Busch eventually returned to complete the press conference.
This season has been a bit of the same for Busch. He's had an up and down year, sitting a stout seventh in points but having endured plenty of criticism – much of it from Stewart himself – for overaggressive driving. And once again a would-be triumph at Phoenix was partly overshadowed by adversity, as Busch came here on the heels of being ticketed for reckless driving – though based on Busch's explanation, the charge sounds far worse than the incident actually was.
And after winning the pole Thursday, he once again had a moment that should have been purely celebratory. But there again was an obstacle, though this time it wasn't the media and it wasn't his brother.
No, at Phoenix on Thursday, it was a majority of the fans who let Busch know exactly how they felt about his success.
But instead of complaining, storming off or even directing a colorful gesture toward the unsupportive crowd, Busch had fun with it with an odd celebration that one reporter described as a "wall dance."
"The fans were giving me great inspiration to go over there and give them a little celebration," Busch said. "They were calling out my last name I believe – 'Buuuuuusch.' – so I just thought I would give them a little love. … It is all in fun. I have a good time with them."
Busch knew he actually was hearing boos, and he had fun with it. Being vilified by fans is something his brother – who has taken to doing snow angels after wins, leading Stewart to sarcastically suggest Kyle follow suit – also has to deal with on a frequent basis.
Kyle Busch thinks that's just fine. In fact, he says he feeds off it.
"Dale Earnhardt said it best many years ago [that] it isn't about whether you are getting booed or cheered, it is all about who has the most noise," said Busch, who suggested that Jeff Gordon and Dale Earnhardt Jr. are neck and neck atop the fan noise meter. "The Busch brothers are steadily climbing that rope."
In being forced to deal with criticism, Stewart has become a bit more of a good guy – or at least a funny one – while Busch seems resigned to being one of NASCAR's bad boys. And he's enjoying it.
Stewart watched Busch's celebration on a TV monitor.
"Just think, you guys get to talk to him next," Stewart said. "It's all going to go downhill from here."
But it didn't. Nobody asked Busch about that night in November in the Phoenix International Raceway media center, and Busch left the room simply happy to have won the pole.
He wasn't the only one in good sorts as the sun set on PIR.
"Glad we could be here with you guys," Stewart said (jokingly?). "Thank you. Enjoy your evening."
Both Stewart and Busch did just that.