Notice that it is actually also pink, but much paler than 'Autumnalis Rosea' - so pale as to give the general impression of white in flower, as does the Pissard plum.
I would say that the flowers from this specimen and the four or five next to it are basically white, with nary a hint of pink. I may be a bit colour-blind, but in all of the years that I've seen them, these flowers have always looked white to me. These trees are at the west end of Kerrisdale Centennial Park (bordering Yew Street between 42nd and 43rd) on the west side of Vancouver (not to be confused with the West End of Vancouver). They look pretty straggly, with lots of disease in the branches and twigs. The cankers on the smaller stems often girdle them and choke off the tips. Twig-death-by-canker is much like performing a "heading cut" on a branch tip. Such pruning is a big no-no, especially on cherries, because it typically causes a proliferation of twiggy regrowth behind the cut. The presence of tight clusters of shoots not only destroys the line of the branch, but they are often so congested that it increases disease susceptibility. It's your basic positive feedback loop. Infection by the disease causes the conditions that promote more disease infection. The damage looks to me like a cross between a witches' brooms and giant spider legs. Despite the damage and the disease, the plants are still relatively vigorous and produce good flowers every year. Then, once it warms up, the trees go to hell. But then, numerous people have said that 'Autumnalis' types would never win any awards for beauty. They're grown for the sheer joy of having trees bloom in mid winter. I'm convinced that we can grow better 'Jugatsu-zakura' (and all other cherries for that matter) by growing them on their own roots, paying careful attention to the timely removal of diseased growth, and siting them away from road salt, soil compaction, summer drought conditions, winter flooding, shade and traffic. No big deal.
I'm just adding Ron B's comment that he made about 'Autumnalis' in one of the other threads: 'Autumnalis': double palest pink; possibly nearly extinct in this region The issue isn't the colour, as Ron and Doug seem to agree that it's so pale that it appears white. But the "nearly extinct" should be helpful for scouts confused like me. He and Doug described 'Autumnalis Rosea' as commonly seen in this area. Those are described in a separate thread.
The Autumnalis in this photo (same Kerrisdale Park trees) appears much less pink in real life, but the Autumnalis Rosea that have been blooming a long time are looking quite white now too. But the Autumnalis Rosea buds are deep pink, and these Autumnalis buds are white.
If you just showed me those pink flowers on the left or the twiggy habit photo on the right I'd say it was 'Autumnalis Rosea'. I also saw one at Hillier Arboretum that wasn't to me clearly one or the other that day. The less-pink buds of 'Autumnalis' may be the most consistent quickly discerned difference. Perhaps it always has markedly shorter flower stems as well.
Well, have a look at the colour of the buds, particularly in the photos I posted, in the Autumnalis Rosea thread. Not only was the colour very different in real life, but the autumnalis rosea have that long stigma that looks like a tongue sticking out from the buds, and these ones didn't seem to have that. I have no idea if that makes a difference. If one has a descriptor added that means 'pink', then it would seem that the one with the pink buds might have got its name from just that. Not that I write the rules.
They both have pink buds, they're just much more pink with 'Autumnalis Rosea'. With Higan cherries generally there is a behavior wherein the flower first remains closed while the stigma sticks out from between the petals, then the whole thing opens up, exposing the anthers as well as the stigma. Maybe this is a mechanism that controls pollination in the same fashion as similar behavior shown by flowers of magnolias. In the latter case the stigma and stamens are open for business at different times, covering the anthers while the stigma is available prevents self-pollination.