What are Gameplay Tasks useful for?

When checking out the built-in Behavior Tree tasks, I happened across “Push Pawn Action”. I didn’t know what these were, so I searched around until I found the UE4 roadmap (Trello), which states that Gameplay Tasks are done, and that they used to be Pawn Actions. After continuing to search and read the header files, I’ve come to the conclusion that they’re basically objects that are used to generically do things. However, this is mostly speculation, as I have not been able to find a firm answer anywhere.

tl;dr: what are gameplay tasks used for, what are pawn actions used for, and what makes them different?

Would like to bump this for an answer