Substantive signals
Exact words, field weights, semantic similarity, categories and attributes may come back in the score.
Glossary
Relevance Score
A relevance Score is a composite score that allows search to estimate how strongly a product fits a specific search.
Additional signals
Stock, popularity, or merchandising can affect the final ranking, but do not need to be part of the pure relevance score.
Not a universal scale
A score is especially useful within the same search configuration and query context; do not compare values blindly between systems.
Review
Use judgments and online KPIs to check that higher scores really mean better results.