There is afaik no page containing explanation of all the specific permissions you can set up in custom roles. However, I have a list of the less commonly known ones, including the two you ask about:
SocialEngage - This is a portion of Social Studio
Marketo - This is no longer valid
DeveloperApp - This gives the ability to create custom Apps for use with ...
Suppose you had a Master object called SpecialForcesUnit with fields like:
Unit Origination Date
and a detail object called:
TeamMember with fields like:
Clearly some profiles/permission sets should have access to both master and detail but other profiles/permission sets might only get access to the master.