(CNN) There were no scathing personal attacks, no sensational name-calling and no furious mud-slinging.

The fourth Republican presidential debate of the campaign season marked a notable shift from the previous forums that were dominated by fireworks fueled by outsized personalities.

The event, hosted by Fox Business, featured plenty of testy exchanges between the candidates on hot-button issues like immigration reform and national security. But the two-hour affair notably lacked the explosive personal confrontations as candidates sought to focus on drawing out their own policy views — and contrasting their profiles against Hillary Clinton.

There was no single dominant performance as in the past when candidates such as Carly Fiorina and Marco Rubio wowed audiences -- and swiftly improved their place in the polls. Several candidates, including Rubio and Ted Cruz, were strong on the debate stage on Tuesday. And Jeb Bush, who has struggled in such environments, projected greater confidence, seeming to relish a confrontation with Donald Trump on national security.

One of the biggest questions heading into the evening was how Ben Carson would address the series of questions raised in recent weeks about his biography. The retired neurosurgeon and political newcomer appeared prepared with a ready quip, as he blasted the media.

Carson's quip

"First of all, thank you not asking me what I said in the 10th grade," Carson said to applause and laughter. "I appreciate that."

He went on: "I have no problem with being vetted. What I do have a problem with is being lied about."

He accused the press of treating Clinton much more favorably.

"When I look at somebody like Hillary Clinton, who sits there and tells her daughter and a government official that, 'No, this was a terrorist attack,' and then tells everybody else that it was a video, where I came from, they called that a lie," he said.

Carson's comments came after CNN reported last week that nine childhood friends, classmates and neighbors who grew up with Carson said they had no memory of the anger or violence the candidate has described. Notably, Trump, the GOP's front-runner who is facing stiff competition from Carson, showed no interest in going after the neurosurgeon -- despite delighting in slamming him at campaign events this week.

The debate came at a crucial time in the 2016 race. Similar to Carson, Rubio is under intense scrutiny as his poll numbers have ticked up. But the moderators Tuesday did not bring up the Florida senator's use of a state Republican Party charge card — an issue that his critics have seized on.

Meanwhile, the struggles of Bush -- once viewed as the party's eventual front-runner but now stuck in the single digits -- have created an opening that his peers are jockeying to fill. Bush has delivered underwhelming performances in past debates, and on Tuesday appeared prepared to give punchier responses.

While the event lacked some of the fireworks of previous debates, it did expose fundamental divides on immigration and foreign policy.

Clashing on national security

Bush and Trump butted heads on national security, disagreeing on the role for the U.S. in confronting the rise of ISIS.

"We can't continue to be the policemen of the world," said Trump, who has argued that the U.S. should let Russia take the lead in fighting ISIS in Syria.

Bush quickly shot back.

"Donald is wrong on this," he said. "We are not going to be the world's policemen, but we sure as heck better be the world's leader."

Carson, meanwhile, struggled when asked to address U.S. presence in Syria, offering a meandering answer.

"Putting the special ops people in there is better than not having them there," he said about President Barack Obama's decision to send 50 special operations forces to fight ISIS in Syria. "They're actually able to guide some of the other things that we're doing there."

Immigration reform pitted those with more moderate views such as Bush and Ohio Gov. John Kasich against immigration hardliners like Cruz.

Bush argued that mass deportation of undocumented people currently in the United States is "just not possible and it's not embracing American values."

"It would tear communities apart and it would send a signal that we're not the kind of country America is," he said.

Cruz appeared energized and aggressive in taking on his rivals. He made the case that following the law is not the same thing as lacking in compassion.

"Every sovereign nation secures its borders and it is not compassionate to say we're not going to enforce the laws and we're going to drive down the wages for millions of hard-working American workers," the senator said.

Wage debate

Rubio, who had a standout debate performance last month in Boulder, Colorado, kicked off the prime-time showdown by arguing against raising the minimum wage -- a popular view among Republicans -- and pointing to the success of his own parents despite their humble backgrounds.

"If you raise the minimum wage, you're going to make people more expensive than a machine," he said.

Both Trump and Carson appeared to go one step further, saying wages in general were too high.

Carson, the only African-American presidential candidate this cycle, said "high wages" were at least partly to blame for high unemployment among black people.

Trump argued that wages were "too high," and that raising the minimum wage would hurt economic growth.

Rubio also pressed for stronger vocational training, again seizing a moment to present himself as an advocate for the middle class.

"We need more welders and less philosophers."

Carson, Trump, Rubio, Cruz and Bush were joined by John Kasich, Carly Fiorina and Rand Paul for the prime-time showdown.

Lower-tier candidates

Four lower-tier candidates --- Chris Christie, Mike Huckabee, Bobby Jindal and Rick Santorum --- kicked off the evening with a one-hour "undercard" debate. Christie and Huckabee had qualified for the main debates in previous gatherings.

Christie, known for his bold style, used the earlier debate to repeatedly slam Clinton -- part of a strategy to make the case that he could take on the Democratic front-runner during a general election.

"If you listen to Hillary Clinton," Christie said, "she believes that she can make decisions for you better than you can make them for yourself."

The New Jersey governor, whose political fortunes have fallen drastically following the state scandal dubbed "Bridgegate," also called on Republicans to train their fire on Clinton rather than each other.

"She is the real adversary tonight, and we better stay focused as Republicans on her," he said. "Hillary Clinton's coming for your wallet, everybody. Don't worry about Huckabee or Jindal, worry about her."

Jindal made a contrasting case, insisting that not just any Republican was capable of taking on Clinton.

"Let's not just beat Hillary -- let's elect a conservative," Jindal said, before going after Christie for his record in New Jersey. "Records matter."

Tempers flared at the media when a moderator asked each of the candidates to name a Democratic member of Congress they admire the most.

"I think this is why people were so frustrated with the last debate, with these kinds of silly questions," Jindal shot back, adding that he would fire everyone in Washington as president.

The other three candidates declined to engage the question, offering up unrelated answers.

Lindsey Graham and George Pataki did not qualify for either debate.