Dimensional differences between Weaver-style and Picatinny bases???

[str8flite]

I have a 2 piece Ed Brown tactical base that is listed as fitting Weaver style rings as well as Mark4 rings (p/n: 52083) listed as being Weaver style, but can I mount Picatinny spec rings to a Weaver style base? The base looks just like picatinny rail but what are the differences in mounting surface, angle of the sides, slot spacing and so on?

 

[LouBoyd]

This discussion of Weaver vs Picatinny is on Brownell's site. I think it sum up the situation pretty well:
http://www.brownells.com/.aspx/lid=...y_Rails,_Weaver_Rails,_What’s_The_Difference?