What is the difference between slash n and slash o in sap

Open new transaction screen directly from current transaction screen without opening start page ("SAP Easy Access" screen). You could do this by input T-code into the command field with additional code before of the T-code, which is:

The difference between /n and /o:

If you use "/n" in the command field before the T-code on any SAP transaction screen and press enter, you will go to the T-code transaction screen and the current transaction screen will be closed (any unsaved data will be lost).
If you use "/o" in the command field before the T-code on any SAP transaction screen and press enter, you will go to the T-code transaction screen and the current transaction screen is still opened (just like you open new window/SAP Easy access screen and go to the new T-code transaction screen from there).