Could somebody speak to the contents of the Tolkien: Maker of Middle-earth volume from the Bodleian verses the Tolkien Treasures volume? Mainly, does the Tolkien Treasures volume offer additional material to what's in the Maker of Middle-earth one, or is is really just a selection of the same material made for a more general audience in a cheaper paperback format?

I currently have both in my wishlist from Blackwell's and was planning on buying both, but if Treasures is just repeat material I was thinking of perhaps skipping it.
Advice much appreciated!