The two leaders couldn't be more different.
"Because as we know, relationships between neighbors are pretty complex, and we won't always agree on everything. But because of our deep abiding respect for one another, we're able to successfully navigate those complexities and still remain the closest of allies and friends," Trudeau said today at the White House during a joint press conference with President Trump.
Trump added, "We are going to have a great relationship with Canada. Maybe as good or better, hopefully, than ever before."
Trudeau, 45, is the son of former Canadian Prime Minister Pierre Trudeau. He began his career as a school teacher and advocate for youth and environmental issues before entering politics. Trump made his fortune as a real estate and media mogul.
As Trump received harsh criticism from U.S. allies for his heated and often divisive campaign rhetoric, Trudeau was coined the anti-Trump in several publications and on social media. While on the campaign trial, Trump called for a ban on Muslims entering the U.S. Days later, Trudeau personally greeted dozens of Syrian immigrants in the Toronto International Airport.
"I don't think it comes as a surprise to anyone that I stand firmly against the politics of division, the politics of fear, the politics of intolerance or hateful rhetoric," Trudeau said in a town hall in December 2015 when asked about Trump's campaign rhetoric. "We need to remain focused on keeping our communities safe, keeping our communities united, instead of trying to build walls and scapegoat communities."
The two leaders' differences set the stage for what could be a tense discussion over how to handle the Syrian refugee crisis and defense cooperation in the Middle East.
While president, Trump is battling a court ruling that stops his executive order banning most immigration from seven majority-Muslim countries. After issuing the order, Trudeau, without mentioning Trump's action directly, tweeted a pointed rebuke.
"To those fleeing persecution, terror & war, Canadians will welcome you, regardless of your faith. Diversity is our strength #WelcomeToCanada," the tweet read.
President Trump has said he wants to bring to the U.S. a total of 50,000 refugees worldwide in 2017, down from 85,000 in Obama's final year in office. The Canadian government reports that Canada has taken in over 40,000 Syrian refugees since November 4, 2015 alone.
The number of refugees who come to the U.S. this year could also be affected by Trump’s executive order, which in addition to temporarily barring entry into the U.S. of people from seven Muslim-majority nations – Iran, Iraq, Somalia, Sudan, Syria and Yemen -- also suspends refugee admissions from any country for 120 days and indefinitely bars the entry of Syrian refugees.
While Trudeau may privately find Trump's order in opposition to values of inclusiveness and openness he campaigned upon, the Canadian leader will have little choice but to seek close cooperation with the new administration on other issues, especially trade.
Throughout his campaign, candidate Trump blasted the North American Free Trade Agreement (NAFTA), calling it a "terrible deal, a total disaster for the United States from its inception."
As president, he has indicated he will follow up on his promise to "renegotiate" or "withdraw" from the deal.
"We're redoing NAFTA, we're doing a lot of our trade deals, and we're negotiating properly with countries, even countries that are allies," Trump said on Feb. 2. "A lot of people taking advantage of us, a lot of countries taking advantage of us, really terribly taking advantage of us."
NAFTA, the trilateral trade agreement between Canada, Mexico, and the U.S., was negotiated by President George H. W. Bush, but passed through Congress and was signed into law under President Bill Clinton in 1994. It has gradually eliminated most tariffs on goods traded between the three countries and created one of the largest free trade zones in the world.
But ever since its implementation, the deal has been studied and debated as to how it has affected the American economy.
Studies have shown economists largely agree that NAFTA has produced benefits, which Trump say cost of American jobs.
In a 2012 survey of economic experts by the University of Chicago’s Initiative on Global Markets, all of them said they either "strongly agree," "agree," or are "uncertain" that U.S. citizens have been better off with NAFTA than they would have been if the trade rules for the U.S., Canada and Mexico prior to NAFTA had remained in place. None of the experts said they "disagreed" or "strongly disagreed."
A 2012 report from the U.S. Chamber of Commerce commended the "remarkable results of NAFTA" for the rise in U.S. commerce with Canada and Mexico.
“U.S. trade in goods and services with Canada and Mexico rose from $337 billion in 1993 to $1.182 trillion in 2011. Each day, the United States conducts over $3.2 billion in trade with its North American neighbors,” the report stated.
But while overall trade has greatly increased between the three nations, the U.S. has a significant trade deficit in goods with both of its neighbors.
In 2016, the deficit with Mexico was $63.2 billion, according to the U.S. Census Bureau. It was $11.2 billion with Canada (though the margin of that deficit is falling).
The Economic Policy Institute (EPI), a left-leaning think tank, said that the trade deficit is costing American jobs.
"By 2010, the U.S. had a trade deficit with Mexico that displaced 682,900 jobs," EPI said in a study.
Trump has cited the U.S. trade deficit with Mexico as a reason for wanting to scrap NAFTA.
"You say, who negotiates these deals?" Trump asked crowds at a rally in Philadelphia days after his inauguration. "Not to mention, millions of jobs and thousands and thousands of factories and plants closing down all over our country."
Trudeau, who has defended free trade, has said he is open to discussing a renegotiation of NAFTA with the U.S.
But any renegotiation will take months, if not years. So far the Trump administration has not laid out specific plans for how the deal may be changed. How it is altered will determine if Congress has to get involved.
Trump has already met with top House and Senate members who deal with financial issues including trade and tax reform. A spokesman for Trudeau confirmed in January that meetings between Canadian officials and Trump's advisers about renegotiating NAFTA have already occurred.
During his joint press conference today with Trudeau, Trump said, "We have a very outstanding trade relationship with Canada. We will be tweaking it. We will be doing certain things that are going to benefit both of our countries."
ABC News' Sekar Krisnauli contributed to this report.