Are these two calibers interchangable?? I have a picture of the two and they look identical, are they? If they are different how so. Also is the 270 wsm and the 300 wsm the same case??

The cases are not the same. The winchester is about 100 fps ahead of the Remington. No animal would know the difference.

The WSM and SAUM series are different cases. The way it looks now, the WSMs have a good foothold on the market and the SAUMs will fade. The 270, 7mm, and 300 WSM are all based on the same case.