I'm not a mathematician but on their site it says - "Cosine similarity and Euclidean distance will result in the identical rankings" so I am assuming that would have to be the case?
When you have unit vectors, cosine similarity and euclidean distance always result in identical rankings, even when those unit vectors are assigned at random and have no semantic structure at all. That's because the euclidean distance |a - b|² = ⟨a - b, a - b⟩ = ⟨a, a⟩ - 2⟨a, b⟩ + ⟨b, b⟩ = |a|² - 2|a||b|cos ɸ + |b|² for unit vectors with |a| = |b| = 1 only depends on the cosine of the angle ɸ between the two vectors.