Cotton: is a natural fibre favoured for its breathability - which means it's cool to wear in the summer while warm in the winter. It's hypo-allergenic and so is especially suitable for people with skin sensitivity. It's also long lasting and easy care - it's machine washable.
Denim: is a cotton cloth, characterised by a diagonal weave called twill which is especially strong. It's often but not exclusively blue and most associated with jeans, having its origin in men's hard wearing workwear clothes in the 19th century. Today when used to produce jeans it is often combined with a little elastane which provides a little 'give', and it has also migrated beyond jeans and is a popular fashion fabric.
Violeta by Mango Denim pinafore dress PBUCCON