Integral strikers/tumblers on the 700. If a striker breaks, you own a single shot until it is repaired. The 400 allows for you to replace the striker yourself. I know of two 700s that broke striker/tumblers on the first shot of opening day. May never happen again, but, it wouldn’t matter on a 400.
The English guys will be along with more. They are both satisfactory designs.

Best,
Ted