I thought the Nike model is a Series 2 spec version with the Nike additions?
You're correct. I actually believed Nike had a Series One as well that wasn't water resistant. There is only Series 2 (Water resistant up to 50 meters).
[doublepost=1482422815][/doublepost]
Yes, it is a series 2 watch.
I don't know where he got the idea that the Nike version isn't waterproof, that's complete nonsense.
Nonsense you say? You are also clearly misinforming the OP, the Nike Series 2 is not waterproof, it's Water resistant up to 50 meters. To correct you, listed below is a link disapproving what you stated.
https://support.apple.com/en-us/HT205000