There were similarities and differences between the Confederate States of America and the United States of America. One similarity was with the structure of the government. Both governments had three branches of government. The legislative branch made the laws. The executive branch carried out the laws. The judicial branch interpreted the laws.
One difference between the Confederate States of America and the United States of America was that the President of the Confederacy could only serve one term as President. The length of that term was six years. The President of the United States served a four-year term. There were no limits, at the time, on the number of terms the President of the United States could serve.
Another major difference is that the Confederacy allowed slavery to exist. It was written into their constitution. The U.S. constitution didn't outlaw slavery, but didn't endorse it either. After the Civil War, the U.S. officially banned slavery with the ratification of the Thirteenth Amendment.