What is the difference between vocabulary and grammar?
Do you have trouble differentiating between vocabulary and grammar? To be honest at one time I did.
What is Grammar?
In linguistics, the grammar of a natural language is its set of structural constraints on speakers’ or writers’ composition of clauses, phrases, and words. Wikipedia
Gramar is the whole system and structure of a language or of languages in general, usually taken as consisting of syntax and morphology (including inflections) and sometimes also phonology and semantics.
In simple terms grammar is the rules of a language that govern all the elements which includes the words, sounds, sentences, writing, combinations and interpretation
What is Vocabulary?
Vocabulary is all the words known and used by a person in a particular language. Vocabulary changes with the times and is constantly evolving.
A vocabulary, usually developed with age, serves as a useful and fundamental tool for communication and acquiring knowledge.

Types of Vocabulary
LISTENING VOCABULARY
Listening vocabulary refers to the words we need to know to understand what we hear. When you listen to something, you don’t just hear it, but you really pay attention to the sounds.
WRITING VOCABULARY
Writing vocabulary consists of the words that we use in writing.
SPEAKING VOCABULARY
Speaking vocabulary consists of the words we use when we speak. Speak means to talk, to give a lecture or speech, or to use your voice to say something.
READING VOCABULARY
Reading vocabulary refers to the words we need to know to understand what we read. When students know more words, they are more able to understand what they are reading.
FOCAL VOCABULARY
Focal vocabulary is a special set of words, terms, or distinctions that are important to a particular group.
What Is the Relationship between Grammar and Vocabulary?
When grammar and vocabulary are used together they become partners working together to create meaningful communication. When you combine the Words in a language you you then need the rules for combining those words into sentences.
The relationship between grammar and vocabulary is one of partners working together to create meaningful communication. Words in a language are known as vocabulary, while grammar gives the methods and rules for combining those words into sentences. Ideas are communicated when both grammar and vocabulary work in tandem.
https://www.languagehumanities.org/what-is-the-relationship-between-grammar-and-vocabulary.htm