Most of your recent posts have been of the same variety - "Please let me know the difference between X and Y".
That's it. You don't tell us what you think they mean, or why you are trying to understand these differences.
Perhaps it's a language thing.
Perhaps you are preparing for an interview.
Perhaps you are working on a take-home exam.
Perhaps you are in a job where you don't understand what they are asking of you.
Or, perhaps it's something else.
We don't know because you haven't tried to tell us.
Anyway, for this question, here's something for you to read. To me, it will show you how 404 and 505 have pretty much nothing in common. But after reading it, you may still have questions. And you may be able to express those questions better.