Tagalys search results are based on the 'AND' function to ensure 100% accuracy, where products displayed in the search results must contain ALL the search query words or synonyms of the words.
'Partially Match' is used in a Merchandised Search when the merchant wants to display certain products in search results when merchandised search term is also a part of the search query.
For e.g., If the word 'Dress' is set to 'Partially Matches' in a 'Merchandised Search' to show four products in a static position, any query that contains the term 'dress' will showcase these 4 products in their static position.
The search results would show products that match the 'Merchandised Search' when the word matches the search query. 
It also displays the same results when part of the search query matches the 'Merchandised Search'
'Partially Matches' is used in 'Search Redirects' when the merchant wants to direct the visitor to a URL for any search query that contains the words.
For e.g., the word 'Gift card' is set to 'Partially Matches' to be redirected to the URL https://example.com/giftcard.
When the visitors search for the words 'gift' and 'card' in any order, they would be redirected to the URL https://example.com/giftcard.