"Lie" implies that the person knows the truth and is deliberately saying something that conflicts with it. However the sort of people who spread misinfo doesn't really care about what's true or false, they only care about what further reinforces their claims or not.
And this right here is why I like the Fediverse. Not immediately presuming the absolute worst case scenario and confidently asserting such, refusing to hear anything to the contrary? Offering kindness as well as accuracy in your answer? You didn't go for the jugular in trying (even if failing) to "pwn" your victim!? You, sir, would make a very bad modern Redditor 🤪. Which is why I hope you stay here, where I can keep getting to read amazingly kind replies like these:-).
The difference is, that with lies, you have to know it is untrue and say it anyway, where with misinformation, there is a possibility that the one telling it believes it is true.
Well that is how I understand the word lying defined:
Say something you know is not true in order to manipulate others.
Or again different said: a lie is always misinformation, but misinformation is not always a lie.