There's a difference between slang and regional expressions, isn't there?

What about words like y'all and younz? I think those words can be considered regional. But there are racial and ethnic differences even there. For instance, I've heard that 'younz' is a Pittsburghese way of saying y'all {that contraction of you all that I don't really know how to spell}.

But I have never heard a Black Pittsburgher say 'younz'. I wonder why that term is considered 'white talk'.

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Also, what about 'sidditty' or 'high siddity'{meaning "stuck up"-meaning a person who has "too high an opinion of her or himself"}. Imo, 'siddity' comes from the word 'society'. Another word for siddity' is 'snooty".

I don't recall hearing "siddity" when I was growing up in Atlantic City, New Jersey. I believe we said that a person was "snooty" instead. But I left New Jersey in the mid 1960s so I might be mistaken about that.

I'm interested in knowing if "siddity", "high siddity", "stuck up", and/or "snooty" cross racial lines in the USA and also if they are known & used elsewhere.