What is the difference between the French words 'des' and 'les'?

That one is a plural definite article and that the other is either a partitive or possessive is the difference between the French Words des and les.

Specifically, the Word des can be a partitive construction which means "some". Or it can be a possessive formed by combining the preposition de ("of") with the feminine/masculine plural definite article les ("the"). Either way, the pronunciation is similar to that in the English noun "day".

The Word les is a definite article which may precede the plural form of feminine and masculine nouns. It is translated as "the". Its pronunciation resembles that of the English noun "lay".