Explain how RIO.Vector relates to Data.Vector?

[ntc2]

Just started using rio and noticed that for most container types the RIO.<container> is similar to Data.<container> (well, the Strict variant). But for Vector, the RIO.Vector is not like Data.Vector, and I'm not sure why. Some explanation in the Haddocks would be helpful.

I should say: I don't have much experience with Vector, so maybe the asymmetry here would be obvious if I did. But I don't, and it isn't :)