The four living former U.S. presidents differ politically and in many ways — including how they spend their time outside 1600 Pennsylvania Ave.

Two years ago, former President George H.W. Bush, who died in 2018, met with all former presidents one final time during the One America Appeal, a drive to raise money for victims of hurricanes Harvey and Irma.

Barack Obama:

Former President Barack Obama and former first lady Michelle Obama attend a ceremony as their official portraits are unveiled at Smithsonian's National Portrait Gallery in Washington in 2018.  (AP Photo/Andrew Harnik, File)

The youngest living president, Barack Obama, and former first lady Michelle Obama have stayed quiet about the 2020 presidential race as Democrats search for their next candidate. Meanwhile, the Obamas have racked up a few lucrative business deals.

In February 2017, they signed a joint deal estimated at $65 million to publish their memoirs. Michelle Obama's best-seller "Becoming" was released in 2018 and Barack Obama's could be released this year. They also signed a multiyear Netflix deal to produce their own movies and shows through the newly formed company, Higher Ground Productions.

Since leaving the White House, the Obamas have purchased an $8.1 million mansion in Washington, D.C., and vacationed with Richard Branson on his private island in the Caribbean, then in Italy, French Polynesia, Indonesia, and, most recently, Hawaii.

The former president did speak out, in a Facebook post in 2017, about President Trump's decision to rescind the Deferred Action for Childhood Arrivals (DACA) immigration policy. He also spoke at the late Sen. John McCain's funeral and talked to students at the University of Illinois at Urbana-Champaign. His fee was reportedly as high as $400,000 for speaking engagements in 2017.

President Obama helped daughter Malia move into Harvard University and showed up for jury duty in Chicago.

The Obama Foundation plans to build the Obama Presidential Center in Chicago, expected to cost the city $175 million in infrastructure changes.

George W. Bush:

Former President George W. Bush speaks at the State Funeral for his father, former President George H.W. Bush, at the National Cathedral, Dec. 5, 2018, in Washington. (AP Photo/Alex Brandon, Pool)

Former President George W. Bush had to say goodbye to his father and fellow former president at the end of 2018. Two years prior he campaigned for his brother, Jeb Bush, in the 2016 Republican primary. He reportedly did not vote for Trump in the 2016 election.

At a Dallas Cowboys game last year, in the city where he and former first lady Laura Bush now live, Bush sat with Ellen Degeneres, drawing criticism from some in Hollywood. In another friendship that caught the eye of the public, Bush and Michelle Obama sat next to one another at both McCain and H.W.'s funerals, where Bush passed Obama a mint — a gesture that became a viral, lighthearted moment.

In February 2017, he released "Portraits of Courage," a book about veterans. In May 2019, on the 10th anniversary of former South Korean president Roh Moo-hyun's death, Bush drew a portrait of Roh to give to his family. Bush also likes to play golf, getting his first hole-in-one last March.

Bill Clinton:

bill and hillary clinton buy house

Bill and Hillary Clinton during the 2016 election. (2016 Getty Images)

Former President Bill Clinton has been in the spotlight since his wife, former Secretary of State and first lady Hillary Clinton, lost her bid to President Trump in 2016.

With Trump's Senate impeachment trial, the era of #MeToo, and the mysterious death of convicted sex offender Jeffrey Epstein sparking questions about his relationship with them, the Clinton name has not appeared in many positive headlines recently.

Newsweek described this once-Democratic power couple as being "in exile" seeking both "attention" and "audience." In 2018 and throughout last year, the couple toured cities offering "An Evening with the Clintons" with slow ticket sales and many empty seats.

The Clintons, who live in Chappaqua, N.Y., are once again back in the headlines as Hulu is set to release a documentary series called "Hillary."

Jimmy Carter:

In this 2019 file photo, former President Jimmy Carter teaches Sunday school at Maranatha Baptist Church in Plains, Ga. (AP Photo/John Amis, File)

At 95, former President Jimmy Carter is the oldest living former president in U.S. history.

Carter leads a fairly normal and frugal life. He lives on a ranch he built himself in 1961 in Plains, Ga., and shops at Dollar General. In 2017, a video went viral of him shaking hands with passengers on a Delta flight from Atlanta to Washington as he boarded the commercial flight.

Toward the end of 2019, Carter fracturing his pelvis during a fall, underwent successful brain surgery and received treatment for a urinary tract infection. In one of his latest public appearances, he appeared in good spirits teaching Sunday School at the Maranatha Baptist Church.