How are silver and Dom white different?
Silver turns gold/red shades to white.
Dominant White turns black to white.
If you start with a gold and black chicken (example: Gold Laced Sebright), you can add Dominant White to make that black lacing go white. Now you have a Buff Laced Sebright (white lacing on gold). Or you can start with the same Gold Laced Sebright but change the gold to silver, so you have a Silver Laced Sebright. Or you can add both Dominant White and Silver, so you have white lacing on a silver chicken, but that just looks white, so people typically don't bother (it sometimes shows up as questions like "Why did I get white chicks when I crossed my Silver Sebright with my Buff Sebright?")
And is partridge dominate or recessive to other colors?
Partridge is caused by quite a few genes working together. Some of them are dominant, some are recessive.
Silver is dominant over gold. So Silver Partridge is dominant over normal Partridge.
Extended Black (turns the whole chicken black) is dominant over the genes that allow gold-and-black patterning, so Partridge is recessive to solid black.
Dominant White would turn the black parts of the Partridge pattern into white, so the normal Partridge is recessive to whatever you call it when Dominant White is involved.
There are a lot of genes involved in how the black & gold are arranged on the chicken, to make Partridge or Lacing or Columbian or Spangling or various other patterns. Some of those are dominant, some recessive, so there's no simple answer to whether Partridge is dominant to other patterns of gold/black.
These are not all the genes that are involved in actually making a partridge chicken, just some examples to show that it is not as simple as a yes/no answer for whether Partridge is dominant.
Recessive white is recessive to Partridge or to anything else (one recessive white gene does not make any visible change), but two genes for recessive white will make the chicken white no matter what other genes it has. So a chicken that has all the other genes to be Partridge, but has two recessive white genes, will be white. I suppose you could say that Partridge is dominant over recessive white, but I find it easier to think of recessive white as it's own thing-- almost like dipping the whole chicken in whitewash. It doesn't change what other color & pattern genes the chicken has, just hides the effects.