Fuzzy queries take a single user-provided term and produce several Lucene TermQuery variants, each of which are boosted with a score that reflects the edit distance (the boost for a non-fuzzy query term is usually 1.0 i.e. no boosting effect.). This used to be mixed in with the usual Lucene IDF ranking but to ill effect [1]. Modern versions of fuzzy query now "lie" about document frequencies of the auto-expanded term variants to prevent IDF issues like this one linked.
[1] When searching for 'Boss' with fuzziness, get higher score for 'Bose' than 'Boss'. ? How Comes !?!?