Different orgs use different style guides as some have already said. In almost all Black is capitalized, whereas white is rarely capitalized but you still see it occasionally.
I’m torn on white/White personally. The reason given by most is that it falls in line with white supremacist rhetoric, and generally has been capitalized exclusively in that context. Totally valid argument to not use it for that reason.
On the other hand I think leaving it lowercase risks making it an assumed default state, or makes it so that white people think of “racial” issues as something that does not include them. Plus allowing white supremacists to decide what is or isn’t whiteness and how we talk about it I think is a bad idea…
More from the AP blog here on their use of Black/white.