Only Gulls

Every Tuesday and Saturday along with the open market in Rotterdam comes hundreds of Gulls. And to be very honest I had no idea what these guys are and how to differentiate them from each other. But it seems for now, these fellows who appear here are not that difficult to ID.
So as a sort of Gull ID tutorial I have put together this series on two of the larger species we have here - The Herring Gull and the Lesser Black-backed Gull.

Also managed a few decent flight snaps of both species.

But I don't have such comparative analysis of the juveniles. Only Herring Juniors here.