MacKenzie Scott and Melinda French Gates have committed more than $28 billion to philanthropy through two very different approaches. Scott has donated more than $26 billion through unrestricted, trust-based grants, allowing nonprofits to decide how to use the money. French Gates has focused her giving through Pivotal Ventures on women's health, families, economic opportunity and gender equality. Their contrasting strategies are helping reshape modern philanthropy and the way billionaire wealth can create lasting social change.