Concept Framework is the name I have given to approaches that focus on how best to communicate a game concept and the methods that support this (e.g. guidelines, templates, presentations, or rules).
As a game design tool, a concept framework helps formulate tangible ideas, which allows others to evaluate them easier. A concept framework works best as a tool for the concept phase of the game design process, but can also be used as a way to later evaluate your design during the design and tuning phases to determine how much as changed since the original idea. Because most game development is dependent on a concept being accepted by a publisher, a developer, a producer, a development team, a commissioner, crowd sourcing, etc. it is important to be able to communicate it in the best possible way. Having a framework helps provide some standards in what and how a concept is communicated.
(1) High vs. Low
A concept framework may focus on helping the designer communicate a high-level (brief) or low-level (detailed) game concept. During the process a designer can move from high-level to low-level with any concept. The advantage of high-level concepts is that you can potentially create several in a short period of time, while low-level concepts require more time cover the details about the game development (e.g. game-play, narrative, tech issues, etc.).
(2) Pitches or Documentation
Some concept frameworks focus on documentation or presentations. In general, the guidelines provided by these approaches provide the essentials for communicating the game concept. Documentation can range from single pitch sentence to 4-5 page concept document.