Here's a breakdown:
* Vocabulary: The set of words that a person knows and uses.
* Lexicon: The complete set of words in a language. It can also refer to a person's individual vocabulary.
So, when someone says "vocabulary lexicon", they're simply emphasizing that they're talking about the entire collection of words someone knows or a language possesses.
Here are some examples of how you might use these terms:
* "Her vocabulary lexicon is vast; she can speak multiple languages fluently." This means she has a wide knowledge of words in various languages.
* "The lexicon of the English language is constantly evolving with new words being added and others falling out of use." This emphasizes that the total number of words in English is vast and dynamic.
In most cases, using just "vocabulary" or "lexicon" is sufficient and clearer.