indistinguishable; hard to tell apart
Rare idiomatic expression comparing something to a white egret in snow, where the two blend together and become indistinguishable. Used to describe things that are so similar they cannot be told apart.
'Yuki ni shirasagi' refers to something being indistinguishable, like a white egret in the snow.
A classical Japanese simile: a white egret standing in snow is hard to see, hence 'indistinguishable'. The exact origin is uncertain, but it appears in traditional poetic and proverbial contexts.