Because the Southerners pretty much made a confederacy, breaking away from the Union. Another reason is that the South had slaves, the Union did not
They did not recognise the Confederacy as a sovereign nation. They regarded it as a collection of states in rebellion against the US
IMPROVEMENT
.....and they called them "rebels" or "Johnny Reb" or "Goddamn secessionists"
because they are not southerners they keep away from them
The Southerners were called Rebels. The Northerners were called Yankees. The spellings are the same today.
Because the southern states had rebelled against the USA.
The northerners were called Rebels or Johnny Reb .... Southerners were called Yankees or Billy Yank .
Because those states were in rebellion against the USA
Northerners were called the Union. Southerners were called the Confederacy.
Rebs (short for Rebels) and seshes (short for secessionists) were two.
Scalawags
Southerners were delighted with the Dred Scott decision, but northerners were outraged.
The northerners were called Yankees and the Southerner were called rebels.
The Northerners called it Bull Run, the Southerners Manassas.
The southerners wanted slavery to end but northerners didn't want that