The Ameraucana Breeders Club site shows the difference in their "scrapbook" of photos - The Wheaten hen should be of wheaten color but with black primary feathers and tail feathers, the Blue Wheaten should be of a lighter, creamier type Wheaten color but with blue primaries and secondaries.
I wish my W/BW Ameraucanas were old enough to show you, but I do have W/BW Marans pullets to show the difference.
With my current Marans girls and their plumage so far I'm not liking the brown flecking in the chests and too dark of "lacing" in the backs, but who knows. . . They're pullets anyway. But looking beyond SOP - The blues still are prettier, at least in Marans.