See Also
Trailhead has a nice overview of Page Layouts https://developer.salesforce.com/trailhead/force_com_introduction/customizing_user_interface/ui_page_layouts
Different Layout Types
Compact Layouts are for the Salesforce1 Mobile App. Mini Layouts are for Hover links and the Console.
Compact Layouts
https://help.salesforce.com/HTViewHelpDoc?id=compact_layout_overview.htm&language=en_US
https://help.salesforce.com/HTViewHelpDoc?id=compact_layout_notes.htm&language=en_US
Custom Buttons and Links
Trailhead has a nice overview https://developer.salesforce.com/trailhead/force_com_introduction/customizing_user_interface/ui_nav_buttons_links