What is the difference between the 5-Act structure and the 6-Act structure of storytelling?

Question

There is a YouTube channel called 6-Act Structure, which I will be citing as a reference, run by an Marshall Dotson who wrote The Story Structure Secret: Actions and Goals. The author argues in favor of the 6-Act structure. I found his explanations on how stories fit into the 6-Act structure confusing, and I don't understand why the Act-5 (resolution) and Act-6 (new world) of the 6-Act structure are not the same act as it is in the more traditional 5-Act structure.

I have the following questions:

1. What is the protagonist's goal in each act of the 6-Act structure and in each act of the 5-Act structure?
2. What is the protagonist's goal in the 6th act in the 6-Act structure?
3. How does the 6-Act structure justify the need to divide the 5th act of the more common 5-Act structure into the 5th and 6th acts? I feel that there is no goal for the protagonist in the 6th Act of the 6-Act structure. I think the story had already ended in the 5th act, but I want to understand the usefulness of the 6-Act structure.
4. What is the definition of an act in the 5-Act structure proposed by John Yorke in his book Into the Woods?
5. What is the definition of an act in the 6-Act structure?

Please use the following videos as the movie references for the 6-Act structure because Dotson uses these movies to illustrate the 6-Act structure. I want help understanding these video breakdowns from the 6-Act Structure YouTube Channel:

1. Movie Structure Breakdown: The Empire Strikes Back
2. Movie Structure Breakdown: BACK TO THE FUTURE
3. Movie Structure Breakdown: Avatar
4. Movie Structure Breakdown: Wreck-it-Ralph

Answer 1

The difference is that the 6 act structure has six acts and the 5 act structure has five acts.

Jokes aside, there is no such thing as "The Five Act Structure" or "The Six Act Structure".

There are many five act structures, and probably at least a few six act structures. Anyone can come up with their own theory of story structure, and many writers use slightly different definitions of an "act" to accommodate their structure.

If you do not find a particular person's structure to be useful or enlightening, you are perfectly entitled to simply ignore it. If you think the distinction between acts five and six is weak, you can continue to treat them as one act if you wish.

Trust your own judgement. This is just some guy on Youtube, not an experienced academic. If you think his definition of an act is unclear and his structure isn't meaningfully different from a five act structure, you're probably right.