Eleven subspecies of the White Wagtail (Motacilla alba) are currently recognised and they all have slightly different plumages.
This is Motacilla alba alba, the nominate subspecies of the White Wagtail which occurs on the European continent and migrates down as far as Kenya.

Top, Left & Middle: Histria area, Constanta County, Romania, 21 May 2018
Right: Mila 23 area, Danube Delta, Romania, 24 May 2018
Last: A juvenile. Babadag Forest, Babadag, Constanta County, Romania, 22 May 2018