Basically, the conventional forces can do any of the missions listed in your two boxes. Note that the law says that SOCOM is on the hook for the special operations facets of all those missions, not the pure or total mission [JMM emphasis].

A, C and I on the upper chart can certainly be SOF missions but they are not exclusively so. Item D there and the application of items F and G can also leave the 'special' definition and become quite mainstream.

Same thing applies to your second chart. Items A, D, E ,F and G are not at all SO peculiar. Even Item D, which nominally is that can also be parceled out to conventional forces when things get busy.
because sec. 167(j) is clearly phrased inclusively, not exclusively, with respect to SOCOM:

(j) Special Operations Activities.— For purposes of this section, special operations activities include each of the following insofar as it relates to special operations:

(1) Direct action.
(2) Strategic reconnaissance.
(3) Unconventional warfare.
(4) Foreign internal defense.
(5) Civil affairs.
(6) Psychological operations.
(7) Counterterrorism.
(8) Humanitarian assistance.
(9) Theater search and rescue.
(10) Such other activities as may be specified by the President or the Secretary of Defense.
Also pretty much totally clear as to John's succinct explanation; except as to this one:

I would not, for example want to give the Ranger Regiment the mission of training Afghan Rangers...
Does this mean that the 75th is capable of performing its ranger mission, but incapable of transmitting that knowledge to trainees ? Maybe so, but that seems odd to me, since I can't think of a legal analogy.

I also understand the distinction between SF and non-SF (Rangers, CA and POG) as explained by John - and how it could be a source of friction. What I perceived (in at least one of the posts) as friction between SF and JSOC is really lost on me - I can only infer it is really inside-inside baseball.

Coming back to the OP question - "what in their view is the dividing line between GPF and SOF" - the answer seems to be that the lines are pretty well drawn from a legal standpoint - and organizationally.

One could I suppose question why CA and POG are in SOCOM; and probably a zillion other questions as to why this or why not that. I'd like to hear all of them. This is a very interesting area of the law in the process of development - Common Article 3 and the "irregular combatant" (which legally is different from the current buzzword "irregular warfare").

Hey, Boot, the US Marines have been doing special ops in "gray-space" areas since at least Puerto Plata - 1800 - my CFMs much earlier. They both attained and retained the art of shape-shifting from porpoises to land crabs. As they say, colonialement.