For myself, HP and the works of Tolkien were different in one very profound way: Rowling was telling a story. Tolkien was attempting to create a mythology. The depth of thought and work that goes into the latter runs far deeper, IMHO and it was something I appreciated even when I first read LotR at age 11, back in the mid 1960s. I still appreciate it today. HP didn't work for me the first time I read the word "muggle." But to explain all the whys and wherefores would take more energy than I have at the moment (and possibly take years and cost millions of lives
).
As to the person with the venomous "I'm right" attitude alas, I've seen that so often over the years, it's something I've come to expect the minute someone begins any discussion comparing one thing to another. "My current favorite fandom, right or wrong (and next week, I'll have a new fave and be dumping just as viciously on what I'm defending today)" is an attitude that apparently grew quite common with the expansion of a media-oriented culture.
Rowling borrowed from Tolkien. So did Terry Brooks and Stephen Donaldson and a lot of other writers. Where the line between homage and rip-off lies is always vague, but is usually a question of how much of the work is "borrowed," and the amount of original thought the author put into it. *
All IMHO, as ever.