What is the difference between must and filter in Query DSL in elasticsearch?
must contributes to the score. In filter, the score of the query is ignored.
In both must and filter, the clause(query) must appear in matching documents. This is the reason for getting same results.
You may check this link
Score
The relevance score of each document is represented by a positive floating-point number called the
_score. The higher the_score, the more relevant the document.
A query clause generates a _score for each document.
To know how score is calculated, refer this link