bilingual dictionary vs lexicon

bilingual dictionary and lexicon both are nouns.

Word	Noun	Adjective	Verb	Adverb
bilingual dictionary	Yes	No	No	No
lexicon	Yes	No	No	No

As nouns, lexicon is a hypernym of bilingual dictionary; that is, lexicon is a word with a broader meaning than bilingual dictionary:

bilingual dictionary: a dictionary giving equivalent words in two languages
lexicon: a reference book containing an alphabetical list of words with information about them

Other hypernyms of bilingual dictionary include dictionary.

bilingual dictionary (noun)	lexicon (noun)
a dictionary giving equivalent words in two languages	a language user's knowledge of words
	a reference book containing an alphabetical list of words with information about them