What's the difference between 'By' and 'Until'?

What's the difference between 'By' and 'Until'?
The use of those two words is always confusing to me because they are translated into the same word in my native language.

"Can I stay here by tomorrow?"
"Can I stay here until tomorrow?"

"I need your report by next Tuesday."
"I need your report until next Tuesday."

Are they all grammatically correct?
Can you clearly explain when I should use 'by' and when I should use 'until'?

"Can I stay here by tomorrow?" (wrong)
"Can I stay here until tomorrow?" (correct)

"I need your report by next Tuesday." (correct)
"I need your report until next Tuesday." (wrong)


by implies something that needs to be completed *before* a specific point in time.

until implies all the time that passes before a specific point in time in which something needs to happen.

I am sure there are better explanations.

Sorry, the second one isn't completely wrong, but it has a totally different meaning.

"I need your report until next Tuesday." would imply that the person making the statement needs the report now and will return it next Tuesday.