What was a significant difference between the American Colonization Society and the Massachusetts Anti-Slavery Society in their approach to black freedom? Both organizations promoted immediate emancipation and equal rights for African Americans. The American Colonization Society advocated for sending freed slaves back to Africa, while the Massachusetts Anti-Slavery Society championed immediate emancipation and citizenship. Both societies endorsed colonization as a solution to racial tensions. The American Colonization Society favored gradual emancipation, while the Massachusetts Anti-Slavery Society supported immediate abolition of slavery.