Genetically, there are several ways to make white chickens.
--Silver turns gold/red to white
--Dominant White turns black to white
--recessive white turns all feather colors to white
Many white breeds are based on a genetically black chicken, turned white by Dominant White, and often with Silver to make sure no gold leaks through. Such chicks are pale in color.
White Jersey Giants are also genetically black, but they have recessive white instead. That doesn't have the same effect on the chick down.
White Silkies often have recessive white, with genes that would otherwise make a partridge color chicken. I think their chicks are a pale color, so they fit the general pattern of pale chicks/white adults, although they are getting there by yet another combination of genes.
The e-locus alleles have a big effect on chick down color.
This page talks a bit about it:
http://kippenjungle.nl/sellers/page2.html
(Search for "chick down" to save a lot of time scrolling)
A chick that is pure for Wheaten at the e-locus is likely to have quite pale down, no matter what other genes it has. (Obvious exception: Rhode Island Reds, where Mahogany turns the chick red instead of pale.)
Some of the other genes that can also affect chick down:
--Silver vs. Gold (useful for sexlnks)
--Columbian (removes some black, in chick down and adult feathers)
--Dominant White (turns black to white, in chick down and adult feathers)
--Blue/Splash, also chocolate (dilute black, in chick down and adult feathers)
--Mahogany (darkens gold shades to red, in chick down and adult feathers)