I thought a concrete example might help to understand the distinctions.
Say we are using The Parable of the Polygons to help a high school class learn about diversity. This is a wonderful little game that tells a story of how harmless choices can make a harmful world.
The Game for Learning (a.k.a. Educational Game) refers to the actual object: The Parable of the Polygons.
All Games for Learning are ALSO Serious Games (Games for Learning are a subset of Serious Games), and in turn, all Serious Games are also Games.
Note: All digital games are ALSO simulations, but that’s a story for another post.
The Game-Based Pedagogy is the lesson that the teacher created which uses that game.
Game-Based Learning is what the students are doing when they use the game to try and meet the learning objectives.
These two are essentially 2 sides of the same coin:
Gamification is not part of any of these. It is NOT a game, although it may use ideas, mechanics, and other elements that are common in games. For example, the idea of ‘unlockable content’ might be included in a lesson such that students need to earn some pre-determined minimum score on a test, before they can move on the the next unit. This was one of the ideas employed in the highly successful SRA Reading Labs.
Does that help?