I don't know if this counts and maybe someone has already said it
BUT FOR THE LOVE OF GOD "VILLAIN" AND "ANTAGONIST" ARE NOT THE SAME THING.
YES!!! I'VE BEEN SAYING THAT FOR YEARS!!! And yet, people still treat them as synonyms. A villian can be an antagonist but an antagonist isn't always the villain.
Compliment and complement still always get me. At this point, I don't think I'll ever remember which is which! 
My pet peeve is people writing 'defiantly' instead of 'definitely'. It has a completely different meaning and worse, it still makes sense so one has no idea of what the person wants to say. One thing I've always wondered is what happens when such person needs to use the word 'defiantly' in its correct definition? Do they write it the same way?
As for me, English is not my first language so I do make many mistakes but they tend to be mistakes native speakers would never do. My most common one is experiencing vs experimenting. It can be very confusing too. I'm trying to think before using these two words but sometimes I still make the mistake.
This pair's another one I see pretty commonly misused. I'm honestly just assuming they don't know how to spell "definitely". And they somehow end up at "defiantly" believing it's not only close enough, but actually correct lmao
I often swap then and than with each other. Also there, their and they're. And here and hear. I think I mess these up a lot because I'm finnish. In my language every letter has a specific corresponding sound so words are read as they are written and vice versa. Here and hear sound exactly the same and need context "I hear something" / "come over here". In finnish that never happens.
Edit. Actually it happens sometimes (kuusi meaning both number 6 and a spruce) but I still hate that english has so many words that sound the same, lol.
The ones that sound the same are, for me, different than the ones that sound totally different but people think they mean the same, like what I put in my original post: "Envy and Jealousy" Two entirely different meanings but people tend to think they're the same.
Don't worry about having English as a second language being the problem, so many English people still type the wrong "their, there and they're" too often.
Villains can even be protagonists! That distinction is definitely an annoying one, I can see why people mess it up, but it's a good distinction to remember
Exactly! I learned that a good way to check if a character is a villain or an antagonist is that if you retell the story from that character's POV (ex. Harry Potter from, Draco's POV) and the end result stays the same, that character is probably the antagonist. If you retell the story and the end result is drastically different, like if Voldemort won in the end, you've got a solid villain characterf
the words that sound alike are a given but I was wondering more about words that sound different that people interchange them thus the original post of "envy vs jealousy."
OH, GOT ONE.
Keening
I see this very often in steamy scenes and it's lumped with moan/groan/whine/whimper/that sort of thing. But the wailing definition of the word is mournful and is a lament, usually for the dead.
I don't speak English well, it bothers me a lot when I used words wrong without realizing it.
Unfortunately I don't know WHAT words I am using wrong when I'm speaking because no one will tell me because "it's cute / in endearing how you and your family (cause we're all bad at English) keep using words to mean something but they don't mean that." but no one will tell me the word that we're using wrong?????
The only ones I have been corrected on have been by online strangers reading my comic and that was that race/nationality/ethnicity do not mean the same thing. (I was using it wrong in the character profiles, I was using race: but then listing ethnicity's. I was just using the the one easiest to spell because I didn't want to fuck the spelling up)
I have no idea. It's an Onomatopoeia word: one that sounds much like what it describes. (if you already knew that sorry for the explanation.
No doubt they're using a thesaurus and relying only on that. Nope, I take that back. I just put the word "howl" into the manuscript I'm typing and hit the thesaurus and then went down the rabbit hole of other words and "keen" never came up.
I can't imagine using that in a steaming love seen. I just sent the info on to another friend who writes some pretty steamy stuff, can't wait to see what she says. I mean, not even in (mummble mumble letters letters) type of leathery stuff would that be appropriate.
give me anything with more than three letters and I can screw up the spelling. You need to let the people you know to please correct you. A lot of times people won't do it because they don't want to make you feel bad. I inadvertently corrected someone when I was in Sicily and then apologized but he then asked me more about different pronunciations so he was okay with it.