BLACK THORNS, WHITE FLOWERS, GREEN TWIGS

I always find it difficult to distinguish blackthorn flowers from cherry plum. 

Cherry Plum (Prunus cerasifera) blooms earlier (usually) and the flowers are a bit larger and brighter white.  So if you notice a bush covered in slightly off-white flowers it'll be blackthorn (Prunus spinosa)

I think these are cherry plum.

But cherry plum usually flowers at the same time as the leaves open, whereas blackthorn always flowers before bud-burst.

But only the cherry plum has green twigs, so as this photo of flower buds shows, it must be a cherry plum.

Maybe it doesn't matter but it's just a bit of a challenge.