Despite the similarities, Mr. Gates is approaching philanthropy in a fundamentally different way — call it Philanthropy 2.0. Just as Carnegie and Rockefeller were influenced by the vertically integrated, industrial economy they helped to create, Mr. Gates's philanthropic efforts are defined and affected by the less hierarchical, networked economy that he helped to create. With its small staff, strategy of creating partnerships and focus on research and development, the Bill and Melinda Gates Foundation more closely resembles a 21st-century software company than a 20th-century philanthropy.

Image Andrew Carnegie selected charitable causes with broad popular appeal. Credit... Associated Press

"It's a conscious attempt to create a different style of foundation, a strategy of intervention and networks," said Lester M. Salamon, director of the Center for Civil Society Studies at Johns Hopkins University.

Carnegie and Rockefeller were pioneers in bricks-and-mortar philanthropy. After Carnegie sold his steel company to J. P. Morgan in 1901, he plowed his nine-figure fortune into limestone. He built the Carnegie Institute in Pittsburgh and the Carnegie Institution in Washington and seeded the nation with more than 2,800 libraries. "His focus was to uplift humanity, and libraries for him were the best way to reach the broadest spectrum of the people," said Peter Krass, author of "Carnegie."

Libraries have also been a centerpiece of the Gates Foundation's work. But instead of building them, Mr. Gates is wiring them. Working with private-sector partners like Microsoft and Gateway, the Gates Foundation has helped provide computers and technology to 11,000 libraries.

John D. Rockefeller created educational institutions from scratch, building both the University of Chicago and Rockefeller University in New York — the first major institution devoted purely to medical research. But Mr. Gates has a taken different approach to education reform. "The Gates Foundation isn't building schools," said Peter J. Frumkin, professor of public affairs of the Lyndon B. Johnson School of Public Affairs at the University of Texas and author of the forthcoming book "Strategic Giving: The Art and Science of Philanthropy."