"Dw i'n gwisgo dillad ysgol."
Translation:I'm wearing school clothes.
I wouldn't say so. "Dillad" is "Clothes" whereas "Gwisg" would be closer to "Uniform".
So, then, what are "school clothes"? It seems like if it's not a specific uniform then it would just be regular clothes, wouldn't it?
Not necessarily. 'school clothes' would be any clothes that are set aside just for school. Like 'Sunday shoes'. Ordinary really, but set aside for a specific purpose. Does that help?