The sorting that is used for the search results page differs for each search algorithm.

The Exact search has two ways of sorting. This is dependent on on whether the Full text rank feature is checked. This checkbox lets you set whether you want to use Full Text Ranking or use a sorting option from Merchandising > Sorting options.

• Checked:
  Sorting is done using Full Text Ranking. This algorithm determines a score for all found products based on relevance. This may be the amount of times that a search term appears in the searched text.
• Unchecked:
  A sorting option is used. Tweakwise chooses the first sorting option in the template that is linked to the active category. If the active category is the home page, then the 'root' or store view category is used.

Note: If you use 'priority search', then that is the highest level on which products are sorted. After that, 'Full Text Ranking' or the sorting option will be used. Read this article for more information on priority. 
When a match is found in the fuzzy search algorithm, the sorting will be done using the full text ranking algorithm.