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