Can anyone please explain the following:

I have created a CMYK page in Adobe Photoshop CS2 with the following colours C=43%, M=6%, Y=0% and K=0%, I saved it as a TIFF. When I import this graphic into XXP the colours become C=49%, M=12.5%, Y=3.1% and K=0%.

Conversely if I create a rectangle in XXP with the colours C=43%, M=6%, Y=0% and K=0% save that file out as a TIFF, when this file is imported into Photoshop the colours become C=49%, M=12%, Y=3% and K=0%.