What GP wins in the hierarchy?

I'm working on WSUS and controlling it with group policy.  

At present, my top level Server OU has a policy set to Download and Notify and we control that be releasing patches from WSUS.

I now have moved to two policies (one I call AUTO (download and schedule install) and MANUAL (download and notify) and I plan on applying these new policies to the child OUs under the server OU.  

So, once I apply the new GPs to the child OUs, I want to remove the top level that is inheriting to all of the child OUs so that the new policies applied to the child OUs will take effect.  There will be some period of time when the child OUs will have their new GPs and the top level GP applied at the same time.  

So, my question is, when two conflicting GPs are applied, one to the OU and one inherited, which one wins?

Thanks.

Cliff