Trying to name things in a computer data model.
People have a variety of name roles, such as legal name, maiden name, etc.
"The Sultan of Swat" is a nickname or pseudonym of George Ruth. It seems to stand alone. You don't often see him called "The Sultan of Swat" Ruth.
"Babe" is also his nickname, but is often used together with other parts of his name, as in "Babe Ruth". It's more like the "Bobby" in Robert "Bobby" Kennedy.
I've seen "diminutive" as well as "appellation" used.
Are the two kinds of nicknames actually different? And if so, what terms to use?
Update. A few more examples for clarification:
Is Malcolm X a sobriquet, pseudonym, or just his preferred name?
If an Asian student at a western college takes a more western name is that a sobriquet or preferred name?