jmc

If the socks are different, either white and brown, brown and blue, or white and blue can be picked. If the socks are white and brown, there are 4 options for the white sock and 4 options for the brown sock for a total of 16 choices. If the socks are brown and blue, there are 4 options for the brown sock and 2 options for the blue sock for a total of 8 choices. If the socks are white and blue, there are 4 options for the white sock and 2 options for the brown sock for a total of 8 choices. This gives a total of $16+8+8=\boxed{32}$ choices.