Inventors, applicants and academic authors describe the same mechanism in different vocabularies, and a novelty search that relies on Boolean strings and classification codes inherits that blind spot. The document that sinks an application is often a paper or an older patent in a neighbouring field, phrased in a way no searcher thought to try.
Semantic search compares meaning rather than words, so it finds those documents. It also finds a lot of near-misses, and a ranked list with a similarity score is not a search report. What makes the output usable is evidence: for each hit, the passage that matched, mapped to the claim element it bears on, with the queries and databases recorded so the search can be repeated and defended.