To me, the back doesn't look quite as green as I would expect for Owston's, especially on the second photo. The first photo looks slightly greener but I'm not sure if that is partly the result of lighting. There is little contrast in colour between the mantle and wings, which is apparent on the Owston's photo you posted. Also, the eye ring does not look as prominent as shown on photos of female Owston's. But, of course, I have never seen Owston's in life and haven't seen this bird in the field, so I may be wrong!
I think there is a lot still to be learnt about the ID features of females and first-summer males from this group (Narcissus, Owston's and Green-backed).
