I just went through this entire topic and I have read and re-read these definitions that are presented and I wanted to pose a question.
I agree that there must be a certain mindset that is had by persons who practice Parkour. This I do not deny. I do not however see this mindset in the definitions of Parkour. Parkour seems to constantly be defined as performing a series of motions that will quickly maneuver the individual from A to B.
Sebastian's definition of Freerunning seems to be an attempt to define a mindset or a discipline that has it's foundations in the practice of Parkour. When he says "Free your mind, Run over the world", I interpret that as saying that by practicing Parkour, you can reinvent the way you view your surroundings.
I am in no way saying that this is how the term is commonly used. I am simply attempting to use the response that he has already given M2 to attempt to understand his logic.
As a result, I find that this is almost how I use the term Freerunning. I see it as a mindset that uses Parkour as a means to express said mindset, by unconventionally move from point to point through an environment that would otherwise have you move in a less direct manner. It would seem that in order to further the notion of personal expression and freedom of thought, that the inclusion of acrobatics into this practice must be seen as conducive in some manner. So yes, I see Freerun as Parkour with acrobatics, however as I am inclined to follow definitions from the person credited to have coined the phrase, I also include the mindset behind that practice. (Subsequently I think that this is what Deft is looking for, as it defines a mindset, however it does not restrict the practitioner to simply Parkour)
I would however like to see some quote from Belle defining parkour as not just physical actions. The definition that he has created is very unappealing, in my opinion, as it does not, so far as I can tell. I have hear and read that the practice of Parkour carries over into other areas of your life so that you are always looking to overcome obstacles in your way, however that is a result of the physical and not part of the definition. (I suppose my martial arts background has me looking for him to create a system similar to what Foucan has where Parkour is either redefined as a means to an end, or where is part of a specific "way" that one is striving for. Yes, I know that this "way" is there, however if he does not define it then situations such as this can and do arise)
Aside
This is me simply finding the need to type my thoughts on some notions brought up in this thread. I have to warn those who dare to read on that there will more than likely be no resolution to this discussion found in the following. You have been warned
In a response to the "is there a difference ..." question, I have to agree that common necessity of a word that combines the practice of acrobatics and Parkour have changed Freerunning to mean just that. Now I know that people may say that simply changing the meaning of something in common language does not make what you have done is correct. This logic is true with statements or notions, however with language it is the case that it is almost impossible to keep meanings from changing. Languages are used to convey notions or describe things. What seems to be the problem here is that the community cannot agree on a common language (which I am sure is M2's reason for this topic). So how do we come to the concensus on what means what. I can see three options:
1: Defer judgment and definition to a higher authority - This seems to have been M2's initial attempt. The problem that exists is that the current authority is ignorant of the scope of their judgement and wishes to take the path of rejecting the notion that there is an issue that needs to be resolved.
2: Consensus of the masses - This very democratic approach seems to be where this thread is heading. If a majority seems to use a term a certain way, then that is the way the term shall be used. The problem that I am sure will arise with this is that people, despite the fact that they live in a system of government that is run this way, are so wrapped up in personal freedom that they will reject any attempt at creating definitions that are not the same as their own despite the will of the majority.
3: Abandon new terminology - It is always an option to revert to more formal use of a common language to describe actions in more detail to avoid confusion. For example, instead of using the term "Parkour" simply say that you are practicing a method of moving through an environment to quickly traverse a set distance from point to point. The problem with this is that we are always in search of a way of communicating more efficiently, and as such spouting definitions for everything would be tedious.
Where does that leave the debate? As of now, nowhere. As most of us did when the "what is parkour" debate first erupted over on UF, we will have to wait and hope that this higher authority will save us from our dilemma. I hope that you receive a productive response from Sebastian M2, as it would seem that without clarification from him, this topic could be for naught.