Kestrels and buzzards are the only birds of prey ( not talking owls here) that hover, Kestrels are much smaller in size. Female and male birds of prey also differ quite significantly in colour across the different breeds.
The RSPB website is really good, they have a bird identifier and all the breeds of the British isles
Personally I've never had a problem with BOP, we have lots of buzzards, kestrels, sparrowhawks and peregrine falcons but have never attacked the chickens or ducks luckily!