Euclidean distance, cosine similarity and the dot product produce exactly the same ranking when the vectors are unit length, and the proof is two lines of algebra. When they are not unit length, the three disagree, and which one your index uses becomes a decision with consequences. Four metrics...
Source: [Dev.to](https://dev.to/multigrid/distance-metrics-euclidean-cosine-manhattan-hamming-5g02)