-Coinjoin: I have never used this. I have heard about JoinMarket. Not sure how this works
CoinJoin refers to the technique, where JoinMarket is one of many CoinJoin implementation.
-Mixers: This is what im familiar with. But I want to learn how Coinjoin works since stupid authorities now think anyone that wants privacy is automatically suspect of doing something wrong. So I don't want to pay someone after having mixed the coins, then this someone goes into a KYC exchange, gets blacklisted for some reason, gets asked where the money came from, then says "X gave it to me" (in case you make a person to person payment where you are identifiable, this would be an immediate problem)
Some mixer these days claim you'd receive "clean" coin which doesn't trigger their software, although i don't know how true is it. Besides, some exchange also treat coin from CoinJoin the same way with coin from mixer.