Timothy Geithner has spent his life avoiding the limelight. Larry Summers has mostly basked in it.
The contrasting personalities will have to meet somewhere in the middle if President-elect Barack Obama's newly appointed economic team is to make headway in fighting the worst financial crisis in generations.
Differences in style could lead to some sticking points between the two officials, although most believe the relationship will be relatively smooth.
"Although there aren't major principled policy differences between Mr Geithner and Mr Summers, you can expect that there will be disagreements," said Benn Steil, senior fellow and director of international economics at the Council on Foreign Relations.
Only time will tell whether this is a clash of personalities in the making.
Mr Geithner is the consummate facilitator. He is a man of detail and known more for his practical nature than for any ideological flourish.
Mr Summers, a Treasury Secretary in the Clinton administration, is the polar opposite. He is a big-picture thinker and certainly has a reputation for speaking his mind - and sometimes putting his foot in his mouth. Most recently, he was forced to resign as president of Harvard University for implying that women had inferior skills in science and maths.
"Mr Summers is accountable to the President, so he's not going to be able to go on television all the time without the President's approval," said Mr Steil. "I would be very surprised if Mr Geithner and Mr Summers turn out to be duelling banjos."
Mr Obama unveiled his economic team on Monday. Mr Geithner is set to take over the Treasury and Mr Summers will act as Mr Obama's chief economic counsel at the White House.
Mr Geithner has been a backroom dealmaker, highly respected by his peers but largely invisible to the public eye. Even as head of the Federal Reserve Bank of New York, amid the worst financial crisis in generations, Mr Geithner has let the US Treasury do the talking despite playing a key role in a string of rescue packages, beginning with Bear Stearns and AIG and now Citigroup.
Stepping onto centre stage will mean a change of profile for Mr Geithner.
"It's a difficult transition to suddenly be thrust into the limelight and have to deal with reporters, say the right thing," said Ted Ake, head of bond trading at Mizuho Securities, citing a number of gaffes early in Ben Bernanke's tenure as Fed chairman. "But Mr Geithner has the experience to be able to do that right off the bat."
Just as his experience in managing the crisis comforts investors, that might also provide fodder for Republicans in Congress during his nomination hearings.
A relatively obscure institution that first gained prominence during the Clinton years and produced former Treasury Secretary Robert Rubin, the council answers directly to the President.