XML documents can be displayed in different formats using style sheets. CSS is used to control visual properties like colors and fonts, while XSL is used to transform XML documents into other formats like HTML. XSL uses templates and patterns like sorting, filtering, and matching to transform XML. Selectors in CSS identify XML tags to which styles apply, and declarations specify property-value pairs to style those tags. Contextual selectors help differentiate between identical tags. Box model properties like margin, border, and padding position text blocks.