Wand functions vs Image functions

[*void]

From the descriptions in the MagickWand interface doc, I can't seem to puzzle out the operational difference between the "Set or Get Wand Attribute" methods and similarly named methods in the "Magick Wand Image Methods". I assume the difference is probably crucial to my understanding of how the MagickWand interface works.

For instance
MagickSetBackgroundColor
MagickGetBackgroundColor
and
MagickSetImageBackgroundColor
MagickGetImageBackgroundColor

[magick]

MagickSetBackgroundColor() is global and sets a default for all subsequent images and draws. MagickSetImageBackgroundColor() is local and tells the MagickWand API to set the specific attribute for a specific image.