Final answer:
Johnson's Reconstruction Plan sought to quickly bring Southern states back into the Union with lenient terms, while Radical Reconstruction, driven by Congressional Radical Republicans after the 1866 elections, aimed to fundamentally transform Southern society, including the guarantee of civil rights.
Step-by-step explanation:
The Johnson's Reconstruction Plan versus Radical Reconstruction are two contrasting approaches to reintegrating the Southern states into the Union after the Civil War. President Andrew Johnson wanted to rapidly reincorporate the South into the Union on lenient terms, in line with his predecessor, Abraham Lincoln. Johnson's plan included pardoning Southerners and allowing Southern states to have a clear path back to readmission without significant changes to their societal structures. This approach angered many Radical Republicans, who wanted to dismantle the old Southern order, and ensure rights for formerly enslaved people, ushering in sweeping social and political changes including the realignment of Southern society. The Radical Republicans gained control of Congress in the 1866 elections and enacted the First Reconstruction Act in 1867. This act was one of Radical Reconstruction's key elements and aimed at transforming Southern society by placing Southern states under military control, establishing new requirements for voting, creating new state governments, and overseeing the drafting of state constitutions. The Radical Reconstruction effectively controlled the process of reintegrating the Southern states into the Union, pushing for policies that would guarantee civil rights and fair treatment for all citizens.