A spelling mistake is a word that is written wrongly, such as "recieve" for receive. A grammar mistake is a sentence in which the words are spelled correctly but put together wrongly, such as "she don't know" or their where you meant there.
Many people are unsure about the difference between spelling and grammar mistakes, and some mix the two up. That is understandable, because the line between them is not always obvious. A few examples make it much easier to tell them apart.
| Kind of mistake | What goes wrong | Example |
|---|---|---|
| Spelling | the word itself is written wrongly | recieve instead of receive |
| Grammar | the words are put together wrongly | she don't know instead of she doesn't know |
| Wrong word | a real, correctly spelled word in the wrong place | their instead of there |
Speaking vs. spelling
Many people speak well and clearly, yet make spelling and grammar mistakes as soon as they write down what they said. There are good reasons for that. Many English words sound like other words. Many are spelled differently from the way they sound. And silent letters trip up writers all the time.
In speech, none of this matters. Someone who says their and there in the right places never has to decide how to spell them. In writing, they do. If you are unsure about those two and their sound-alike they're, read there, their, and they're.
Spelling vs. grammar
Some people think that a word that is spelled correctly but used in the wrong place is a spelling mistake. It is not. If you mean one word but write a different one, every letter can be right and the sentence is still wrong. That is a mistake of grammar or word choice, not of spelling: the words are spelled correctly, but they are used wrongly.
Some of the most commonly confused words are your and you're, it's and its, and there, their, and they're. Words like these, which sound the same but are spelled differently, are called heterographs, a kind of homophone. Using the wrong one can change the meaning of the sentence completely.
Here are two examples of words that are spelled correctly but used wrongly.
Affect or effect
The drug did not effect the disease, so the doctors had to change it.
The writer spelled effect correctly, but the right word here is affect. Affect is usually a verb that means "to influence". Effect is usually a noun that means "result".
Elicit or illicit
The police were unable to illicit any information from their informant.
Again, illicit is spelled correctly, but it is the wrong word: the sentence needs elicit. Elicit is a verb that means "to bring out" or "to draw out". Illicit is an adjective that means "unlawful".
These two examples show how easy it is to spell a word correctly and still use it wrongly. For more pairs like these, read commonly misused words.
How to avoid both kinds of mistakes
Whenever you use a word like these, check its meaning. Heterographs are hard for most learners at first. A good dictionary helps, because it shows each word in example sentences, so you can see whether you are using it correctly. Always double-check heterographs, words with silent letters, words that are spelled differently from the way they sound, and contractions.
Knowing the most common spelling and grammar mistakes is the best way to avoid them. A checker helps too: the Spell Checker sorts every issue it finds by kind, so you can see at a glance whether it is a spelling, grammar, or punctuation mistake, and the AI Spell Checker reads whole sentences, so it also catches a real word in the wrong place.