How does the match mode work? Which one should I use?

There are two match modes available: AND and OR.

When the AND mode is used, search results will contain products that match the whole query only (e.g.: Red shirt - only Red shirt will be found).

When the OR mode is used, search results will contain all products that match any of the words in the query (e.g.: Red shirt - all products that contain either “Red” or “Shirt” will be found).