One simple example is that the North has the word pop to mean the sugary carbonated drink while in the South the word used to be soda but is now Coke no matter what flavor you wish to drink. Another is the North's water fountain in the school hallway is called a bubbler in the South. The famous y'all in the South means you all whereas in the North it would be all of you. Sometimes it is simply pronunciation; in the North, a slippery road could be described as greasy with an ssss sound while in the South the word would be pronounced greazy with a zzz sound. I hope this is the sort of material you can use in your project.