Hi. I have a niece who went to JAGS a few years ago and have a daughter at Putney High now. From what I can see, they are both quite similar. Academically very strong, so you need to have a child that can manage in that environment. Having said that, not all girls there are geniuses, but you are in a peer group of some very academically able girls. That may suit some more than others.
They are both very established and confident schools, focus on female empowerment and are quite ‘no nonsense’. Lots of opportunities in a miriad of different areas and high quality teaching. I think Putney might have slightly stronger sport and offers rowing. I think if your daughter is quite creative and arty however I might look at other schools as well. If she’s into science, then these would both be great.
If you are applying, I would choose the one that is easiest to get to for your daughter.