In most cases, the document is a word-for-word duplicate of the United States Constitution. The major differences between them was the Confederacy's greater emphasis on the rights of individual member states, and an explicit support of slavery.
Supreme Court nominated by the President and approved by the Senate
Slavery
The constitution forbids the practice of importing slaves from outside the Confederacy, but explicitly states slavery as a right in the following key provision:
No bill of attainder, ex post facto law, or law denying or impairing the right of property in negro slaves shall be passed [by Congress]
The constitution likewise says that all subsequent territories added to the Confederacy will too become slave states (unlike the United States, which previously decided on a state-by-state basis). The legal basis for slavery in the Confederacy is largely presented as an extension of property rights.
Changes from U.S. constitution
The President is allowed to only be elected for one six-year term, rather than an unlimited number of four-year terms (at the time) or a maximum of two four-year terms (today).
Several provisions in Article I which prohibited anyone of foreign birth to vote (Sec. 2, Cl. 1), extended the power of impeachment of federal officials to state legislatures in certain cases (Sec. 2, Cl. 5), granted cabinet officers opportunity to address the House of Representatives (Sec. 6), and gave the Confederate President the power of the line item veto over certain appropriations legislation (Sec. 7, Cl. 2).
The first twelve amendments to the U.S. Constitution, including the ten that comprised the Bill of Rights, were directly incorporated into the Confederate constitution.
Each clause within a section was numbered, whereas in the U.S. constitution clause numbers were only inferred.
In the preamble there is clear reference to "Almighty God", which is not included in the original U.S. constitution.
Georgia: Francis S. Bartow, Martin J. Crawford, Benjamin H. Hill, Thos. R. R. Cobb.
Florida: Jackson Morton, J. Patton Anderson, Jas. B. Owens.
Alabama: Richard W. Walker, Robt. H. Smith, Colin J. McRae, William P. Chilton, Stephen F. Hale, David P. Lewis, Tho. Fearn, Jno. Gill Shorter, J. L. M. Curry.
Mississippi: Alex. M. Clayton, James T. Harrison, William S. Barry, W. S. Wilson, Walker Brooke, W. P. Harris, J. A. P. Campbell.
Louisiana: Alex. de Clouet, C. M. Conrad, Duncan F. Kenner, Henry Marshall.