The difference is simple: filters are cached and don't influence the score, therefore faster than queries. Have a look here too. Let's say a query is usually something that the users type and pretty much unpredictable, while filters help users narrowing down the search results , for example using facets.

This is what official documentation says:

As a general rule, filters should be used instead of queries:

• for binary yes/no searches
• for queries on exact values

As a general rule, queries should be used instead of filters:

• for full text search
• where the result depends on a relevance score

An example (try it yourself)

Say index myindex contains three documents:

curl -XPOST localhost:9200/myindex/mytype  -d '{ "msg": "Hello world!" }'curl -XPOST localhost:9200/myindex/mytype  -d '{ "msg": "Hello world! I am Sam." }'curl -XPOST localhost:9200/myindex/mytype  -d '{ "msg": "Hi Stack Overflow!" }'

Query: How well a document matches the query

Query hello sam (using keyword must)

curl localhost:9200/myindex/_search?pretty  -d '{  "query": { "bool": { "must": { "match": { "msg": "hello sam" }}}}}'

Document "Hello world! I am Sam." is assigned a higher score than "Hello world!", because the former matches both words in the query. Documents are scored.

"hits" : [   ...     "_score" : 0.74487394,     "_source" : {       "name" : "Hello world! I am Sam."     }   ...     "_score" : 0.22108285,     "_source" : {       "name" : "Hello world!"     }   ...

Filter: Whether a document matches the query

Filter hello sam (using keyword filter)

curl localhost:9200/myindex/_search?pretty  -d '{  "query": { "bool": { "filter": { "match": { "msg": "hello sam" }}}}}'

Documents that contain either hello or sam are returned. Documents are NOT scored.

"hits" : [   ...     "_score" : 0.0,     "_source" : {       "name" : "Hello world!"     }   ...     "_score" : 0.0,     "_source" : {       "name" : "Hello world! I am Sam."     }   ...

Unless you need full text search or scoring, filters are preferred because frequently used filters will be cached automatically by Elasticsearch, to speed up performance. See Elasticsearch: Query and filter context.