Illustration or picture might help but each product/library can have its own users, roles and access rights. If the data is stored in separate contexts, you can prevent users of one from seeing data on the other. This applies to searching where you get nothing or if there is a link to an object that the user does not have access to, it will show only number/name and the rest is "Secured Information" preventing further access. If this is what you want to have happen, then you just need to make sure the users are not in both areas. However, if you want to have a BOM or product structure share components, someone would need access to both to create the linkage.
If you are referring to view version (I do not have the Service module installed), then I am not sure you can prevent access to views via ACLs. The ACLs do not go down to the view, just object level. I am not sure its possible to store different views in different folders, but if that was possible, you can configure different ACLS at the folder level to prevent access. Windchill would revert back to another view version like Design if it could not see a downstream view, depending on how you have your config spec setup.
