The European Shag, also called the Common or Crested Shag and the Green Cormorant, has a crest/quiff and a metallic green tinge to its feathers in breeding plumage.
It lacks the yellow throat patch of the larger Great Cormorant but has some yellow where its slimmer beak meets its face.
The names Cormorant or Shag are sometimes interchangeable; in the past "Shag" was applied to a Cormorant with a crest (or double crest) but currently is usually applied to small cormorant species.
(Australian) Pied Cormorant/Shag
The Pied Cormorant, also called the Australian Pied Cormorant or Shag, comes from Australasia. It is smaller than the Great and European Cormorants and has yellow between eye and beak, unfortunately not visible on photos above (against the sky) or below (in bright sunlight).