Many hedges are formed mainly of rows of thorn bushes: either blacktho0rns or hawthorns. A quick way to tell which has been used from a distance is to see whether the leaves or the flowers are breaking first.
Blackthorn flower earlier than hawthorn, and their flowering season is pretty much over before the leaves appear. These blackthorn flowers are the first ones I spotted, when most other nearby trees of the species were still bare. A little later (perhaps now) a thick blackthorn hedge can look from a distance like it’s covered in a white mist.
Hawthorn is the reverse. Leaf buds start appearing about the same time as blackthorn flowers. The leaves will be fully out before the flowers open. When? There’s a clue in an alternative name for the plant: maY.