Along the two blocks of North 17th Street on either side of the Vine Street Expressway in Center City, remarkably different financial trajectories of two religious groups are playing out.

At the headquarters of the Roman Catholic Archdiocese of Philadelphia, south of Vine, church leaders are turning property accumulated over generations - such as cemeteries - into cash in a bid to fill huge financial gaps.

About a block north, the Church of Jesus Christ of Latter-day Saints announced plans this week to build a meetinghouse and a 32-story residential tower next door to its $70 million temple, already under construction. The apartment tower alone could cost $75 million to $90 million, a real estate expert said.

Where do the Mormons get the money?

The Mormon Church expects members to tithe - to donate 10 percent of their income to the church - and puts some teeth into that expectation.

Any Mormon is allowed to worship in a chapel, like the one to be built in Philadelphia, "but only Mormons who adhere to the highest standards of the faith," including full tithing, are allowed in the temple, said W. Paul Reeve, an associate professor of history at the University of Utah.

The highest sacraments of the religion, such as marriage, take place in the temple, and having that access apparently motivates Mormons to give.

Independent surveys show Mormons give more to their church than do practitioners of other religions, said Ryan T. Cragun, an associate professor of sociology at the University of Tampa.

"Even though it's supposed to be 10 percent, we have external evidence suggesting that it is 7 to 8 percent," said Cragun, a former Mormon who studies the sociology of religion.

Catholics give far less, said Charles E. Zech, an economics professor at Villanova University and an expert on church finances. "Rather than tithing 10 percent, a typical Catholic household in this country contributes about 1.1 to 1.2 percent of their income, which is way low not only compared to Mormons but also to other Protestant churches," he said.

How much Catholics and Mormons give overall is unknown.

There are 15 million Mormons worldwide, including 6.3 million in the United States, according to the church website. There were 1.1 billion Catholics globally in 2010, according to a study by the Pew Research Center.

But Mormons are on a growth tear, with 15 U.S. temples under construction and more overseas. There are already 68 Mormon temples in the United States.

The temple rising at 18th and Vine Streets is being paid for with members' donations that are funneled back to the central church offices in Utah. Unlike most new Catholic churches and parish halls, the temple will open debt-free, experts said.

"When these temples are dedicated, they are paid for," said Reeve, who is Mormon.

Less is known about the financing of the 32-story residential tower planned for 16th and Vine Streets. It's a project of one of the Mormon Church's for-profit arms.

"This is basically a big black box. We just have very little information on what's going on," Cragun said.

A recent deal in Florida gives a sense of the scale on which church-owned Mormon businesses operate.

AgReserves Inc., a for-profit affiliate of the church, agreed in November to pay $565 million for 382,834 acres of timberland on Florida's panhandle. The church already owned 290,000 acres of cattle ranches and citrus farms in the state.

Asked for information about the Mormon Church's businesses, a spokesman sent an Internet link to a July 2012 document on Mormon Church finances. This is what the article said about farmland holdings, which are not limited to Florida:

"The church's business assets support the church's mission and principles by serving as a rainy-day fund. Agricultural holdings now operated as for-profit enterprises can be converted into welfare farms in the event of a global food crisis."