What happened, if I understand this correctly, is that our North American bird had its name changed about twenty years ago to match the bird that is called that in Europe. Or maybe it was the peregrine that had its name changed. Certainly your kestrel looks more like our kestrel than the sparrowhawk does.

I remember my brother in law the birder talking about the name change and thinking that it was silly to groom the common names of things like that, because when you want to be really precise you use the latin names anyway, don't you?

Now I'm doubtful as to which bird had its name changed and uncertain how to google it.