The female Common Kingfisher (first three photos) is almost identical in appearance to the male (last two photos).
The difference between the two lies in the colour of the lower mandible. 
In the male, it is black, or in some cases, mostly black. 
In the female, it is orange-red, or in some cases, mostly orange-red.
Young Common Kingfishers have brown legs while adult Common Kingfishers have red-orange legs.

Alamillo Park, Sevilla, Spain, 27 & 28 December 2025