It really depends on what you're reading on HN, if you're reading about acquisitions or gossip or meta commentary like this, then definitely HN != work if you're reading a technical article then definitely HN = work. And I believe they're both useful information, but one of them definitely isn't work.
I would split the hair even finer and say if you're researching how to accomplish a particular task and you serendipitously find an article on HN then you're doing work, but that's pure luck since normally you would be Googling rather than surfing HN. Reading HN "for the [tech] articles" is at best like going to university—you may be preparing for future work, but all this abstract preparation and self-betterment is not the same thing as real work and we would be wise not to fool ourselves.
I actually disagree. I believe abstract self-betterment is as important as what you are calling "real work". There's certainly a balance to be kept between direct production and abstract self improvement but they aid each other in a big way. I would say they are both part of "real work" as long as you don't stray so far into theoretical improvement that you lose sight of getting stuff done.
