...
- If the user's profile does not have access to ALL fields in a section via Field-Level Security, then that section heading will not be shown. Nice to know.
- If the user's profile does not have access to a lookup field to this object on one of the related objects, the related list will STILL be shown on this object. This is not good. This is why you need different page layouts per Profile.
Different Layout Types
Compact Layouts are for the Salesforce1 Mobile App. Mini Layouts are for Hover links and the Console.
...