Francis, who made 47 foreign visits over his 12-year tenure, often grabbed headlines during his trips with surprise comments.
The late pope was also known for giving unusually frank answers during traditional in-flight press conferences with his travelling press corps, one of the few times the leader of the Church interacts at length with journalists.
Leo has a more reserved style and tends to speak from prepared texts. He has only given one exclusive interview in his six months as pope.
"What we've seen so far is a pope who's very careful when he speaks," Rev. Thomas Reese, a Jesuit priest and commentator, said. "But every trip is a risk. There can always be mistakes or fumbles."
In Turkey, Leo and Bartholomew will celebrate the 1,700th anniversary of a major early Church council, which took place in Nicaea, now Iznik, and created a creed that most of the world's 2.6 billion Christians still pray today.
Orthodox and Catholic Christians split in the East-West Schism of 1054, but have generally strengthened their ties in recent decades.
Rev. John Chryssavgis, an adviser to Bartholomew, said the event is "especially meaningful as a sign and pledge of unity in an otherwise fragmented and conflicted world".
Several other Orthodox Christian leaders are expected to attend the anniversary, but the Vatican has not said which.
The Moscow Patriarchate, an Orthodox community closely allied with Russian President Vladimir Putin that severed ties with Bartholomew in 2018, is not expected to take part.
POPE TO COMMEMORATE BEIRUT PORT EXPLOSION
Leo will also visit Istanbul's Blue Mosque, his first visit as pope to a Muslim place of worship, and will celebrate a Catholic Mass at Istanbul's Volkswagen Arena.
Rev. Nicola Masedu, pastor of Istanbul's Catholic Cathedral of the Holy Spirit, said interest in the new pope's visit led organizers to move the Mass from the cathedral to the arena, which can hold around 5,000 people.
Turkey, a Muslim-majority nation, has about 36,000 Catholics out of a population of around 85 million, according to Vatican statistics.
Leo's schedule in Lebanon includes a prayer at the site of the 2020 chemical explosion at the Beirut port that killed 200 people and caused billions of dollars' worth of damage.
The pope will also host an inter-religious meeting and lead an outdoor Mass on the Beirut waterfront. But Leo, visiting five towns and cities in the country, will not travel to the south, the target of Israeli strikes.
Rev. Michel Abboud, who leads the Catholic Church's charity network in Lebanon, told the Vatican's media outlet the pope's visit was one of "solidarity."
"The people will know that, despite all the difficult situations they have gone through, they must not feel abandoned," he said.
[Source: Reuters]