Comment by regularfry

> No, it contains correctly spelled words used in place of other desired words.

If you intend to write a word meaning "actually existing as a thing" and spell it "reel", it is monstrously unlikely that you genuinely thought a word meaning "a cylinder on which flexible materials can be wound" was a suitable substitute. If you did, that would be the use of a correctly spelled (but incorrectly selected) word in place of a desired word: a grammatical error, in other words. However, if you just pick the wrong letters to construct a phoneme, as is almost certainly the case here... yep, that's a spelling error.

To put it another way, imagine that the word "reel" didn't actually exist, and I make precisely the same error, substituting an 'e' for an 'a'. All of a sudden, by your argument, what was a grammatical error is now a spelling error. But the mistake I made hasn't changed, so that makes no sense.

> If you want to correct these kind of errors, you must now a lot about natural language. >... > Anyway, no spell checker in widespread use attempts this

So? The category of error doesn't change with how difficult it is to fix.