To begin, “art” is not a rarified thing, or at least I don’t think it is. It is, simply, the product of the creative exercise. When you write a story or play a song or draw a picture or act on a stage, you are making “art.” Whether it is good art or bad art is another thing entirely — when I write, I can say I am (generally) creating good art, but when I draw, I am mostly creating bad art. But it’s still art, good, bad or indifferent. What makes it art is the act of creative production, not its quality.
Likewise “entertainment” is also not particularly rarified. It’s that which aims to amuse and engage people (or more widely, that which amuses and engages people, whether intentional or not). In a basic sense, if you are writing or composing or drawing or whatever with the intention or hope that other people will apprehend and appreciate what you are doing, that’s entertainment. And again, you can succeed or not succeed, depending on your skill and also the interest and taste of the audience. What makes it entertainment is the intention, not the quality.
I (by and large) agree with John: neither art nor entertainment should be considered rarified or elevated (though definitely appreciated), and his definitions I think are fairly apt. I also agree with his later extension, in that I feel another component to art comes from intention: the desire to express yourself in a creative way (whether others pick up on what you’re trying to express is another matter). Entertainment also can have creative intent, but as the whole essay calls out, there’s a lot of overlap and interrelation between the two concepts.
I think John (and presumably, Neil) hit the nail on the head, though, in this:
Now, what I think Tyson may have been trying to say, and if so is a thing I would agree with him on, is that one’s entertainment and/or artistic diet shouldn’t be only what you already know that you like — it’s worthwhile to make a stretch here and there and try things that you don’t know if you like, and on occasion to learn more about art (of whatever sort) so that when you approach new and unfamiliar art, you have tools to better understand and apprehend what you’ve got in front of you. Always be reaching for the new and always be learning — and as a result, what art speaks to you, and entertains you, will be a larger set than what’s come before. And sometimes you won’t like the art, and won’t be entertained, but that’s all right, too. You’ll know more about yourself through the process.