U.S. President Trump will meet Chinese President Jinping first time this week.

Their summit will be marked not only by deep policy divisions but a clash of personalities between America’s brash “tweeter-in-chief” and Beijing’s cautious, calculated leader.

They may have one thing in common: their rhetoric about restoring their nations to greatness. But the two men differ in almost every other respect, from their political styles to their diplomatic experience, adding uncertainty to what has been called the world’s most important bilateral relationship.

Five months after his election on a stridently anti-China platform, Trump appears to have set himself on a course for collision rather than conciliation with Xi, raising doubts as to whether the world's two biggest economies can find common ground.

Topping the agenda at Trump’s Mar-a-Lago resort in Florida will be whether he will make good on his threat to use crucial U.S.-China trade ties to pressure Beijing to do more to rein in its nuclear-armed neighbor North Korea, which is working to develop missiles capable of hitting the United States.

Trump, a 70-year-old former real estate magnate with no foreign policy experience before entering the White House, has tweeted that it will be a "very difficult” meeting with the veteran Communist Party leader seven years his junior, given Chinese trade practices he says are killing U.S. jobs.

He has also demanded that Beijing do more to “solve” the North Korean problem - his biggest national security challenge - or he will act alone to deal with Pyongyang’s nuclear and missile programs.

Some White House aides believe Trump’s son-in-law and senior adviser Jared Kushner could be an influential moderating voice on how he handles Xi in their talks on Thursday and Friday. Contacts between Kushner and China’s U.S. envoy helped smooth the way for the meeting, according to current and former U.S. officials.

Even so, what worries the protocol-conscious Chinese more than policy clashes is the risk that the unpredictable Trump could publicly embarrass Xi, after several foreign leaders experienced awkward moments with the new U.S. president.

"Ensuring President Xi does not lose face is a top priority for China,” a Chinese official said.

U.S. presidents’ meetings with their Chinese counterparts are usually more tightly scripted than with other foreign leaders, something Chinese officials insist on to make sure they are treated with the decorum they believe befits a global power.

This summit should offer a study in contrasts: Trump impatient, outspoken and prone to angry tweet-storms; Xi, outwardly calm and measured, with no known social media presence.