Did the southern states and the northern states have the same reasons for fighting the Civil War? In other words what did the two sides think they were fighting for, and, how have historians interpreted these issues?

For both the southern states and the northern states, slavery was the primary issue that brought about the Civil War. However, the reasons that slavery created an irreparable rift between the northern and southern portions of the United States were very different.
The agrarian economy of the South depended upon the institution of slavery for its continued prosperity. Although ostensibly the U.S. Constitution at the time allowed slavery, in the North, slavery had been abolished in state after state, and the movement to abolish slavery at a federal level was gaining popularity. After the election of Abraham Lincoln as president in 1860, southerners became concerned that the Republican Party would outlaw slavery throughout the United States, despite Lincoln's reassurances that this wouldn't happen. To ensure their independence and ability to sustain the institution of slavery, before Lincoln's inauguration South Carolina—followed by six other states—voted to secede from the Union.
Then-president James Buchanan refused to recognize the declarations of secession and determined not to give up federally-owned forts that were in the territory of the Southern Confederacy. When he assumed office, Lincoln was determined to preserve the Union. The war actively began on April 12, 1861, when the Confederate Army attacked Fort Sumter in South Carolina.
In summary, we can see that the South's primary reason for fighting the Civil War was to preserve the rights of the states to maintain the institution of slavery, while the North's reasons involved the preservation of the United States as a Union.
https://www.historynet.com/causes-of-the-civil-war