vocabulary

As a noun vocabulary

is a usually alphabetized and explained collection of words eg of a particular field, or prepared for a specific purpose, often for learning.

As a proper noun Khmer is

the national language of cambodia part of the mon-khmer language family.

As nouns the difference between vocabulary and language

is that vocabulary is a usually alphabetized and explained collection of words eg of a particular field, or prepared for a specific purpose, often for learning while language is (countable) a form of communication using words either spoken or gestured with the hands and structured with grammar, often with a writing system.

As a verb language is

to communicate by language; to express in language.

Dictionary is a coordinate term of vocabulary.

Vocabulary is a see also of dictionary.

As nouns the difference between vocabulary and dictionary

is that vocabulary is a usually alphabetized and explained collection of words eg of a particular field, or prepared for a specific purpose, often for learning while dictionary is a reference work with a list of words from one or more languages, normally ordered alphabetically and explaining each word's meaning and sometimes containing information on its etymology, usage, translations{{,}} and other data.

As a verb dictionary is

(label) to look up in a dictionary.