TE -
yes, so many differences. As Tom M mentions, Macdonald seemed the classic extravert, and Leeds the classic introvert: one aiming for a national membership and national and international recognition for his course, the other seemingly content to above all please himself and the members of his own (small and exclusive) club; one promoting for years and very publicly his philosophy/ideals about great golf course architecture and attempting to build consensus among the experts of the day in this regard, the other basically silent on the issue and confident enough to keep his own counsel and be steered by his own lights; one a strong personality who nonetheless wanted/needed the approval of men he respected and to be thought of as a leader, the other also a strong personality but a profound loner, not so much caring at all who approved of him and who he led (or didn't). All of which is to say, a man like Macdonald and a course like NGLA would pretty clearly be the more influential of the two.
But on the other hand, it is striking how early and often Myopia was praised, and clear that Mr. Macdonald knew the course, and knew it well. Here's an interesting snippet from a long July, 1905 article that is mostly about Mr. Macdonald's dream to build the ideal course -- I think at the time the tentative name was the Monte Cristo Club, and the article gets into what Macdonald thought ideal, and the (differing) views of men like Taylor and Low on the subject, and the results of the 1901 survey into the great British golf holes, and Macdonald's plans for a national membership and a Long Island site etc. All very interesting, but in the context of this thread I found these couple of paragraphs pretty relevant:
"There are many good holes on American links, in Mr. Macdonald's opinion, but to reproduce them would gain nothing of the sentiment that clings about the particular holes of the British links, which are most famous in the stories, songs and records of golf....
Mr. Macdonald believes Wheaton to be the best of our golf courses, while he admits that certain holes at Myopia and Garden City are ideal....It is interesting here to note the opinions of some of our leading professionals on the best testing holes in this country. 'All the holes I like best are at Myopia' is the opinion of Will Anderson, the open champion. 'It is the best golf course in the country, if not in the world...'"
I found this interesting because it makes something clear, i.e. Macdonald was aware of Myopia and of its fine qualities, but he had much bigger fish to fry than Leeds seemed to -- he wanted to not only create the ideal golf course and one that manifested the fundamental principles of good architecture, but one that also brought the Spirit of the Game (literally the "sentiment" of British golf) to America.
I don't know how much such two very different personalities with such different goals in mind could have influenced eachother; I'm guessing not too much. They probably shared the same "source" for their educations i.e. the British links and the oldtimers who knew those links courses so well. It would be great to learn who exactly Leeds talked to and met with over there, but he doesn't seem to be telling....
Peter