I think it's enough to read my comments to see that another approach than the one Gilles took, can be taken:
I voted as unclear because I don't know where to start.
The title said, at various points (I'm not sure what it was when I voted on it):
- What is the difference between mask and umask?
- Understanding the possible difference between mask and umask
The body had hyperlinks to "bit" and "stream" and "bitwise operation" that could have added relevance, but were just definitions (that anyone could look up). IMHO, adding links brings some importance (focus, or important background) to those terms, but here -- IMHO, they're distracting as hyperlinks. Use your own words to describe your understanding of them.
The question then broadens in scope by saying "used ... upon basically any type of code", which is a tenuous claim, IMHO.
The final (at that point) part of the body asked the Question:
How does a mask differs from umask, if at all?
... where you haven't demonstrated any part of your understanding of
umask for an answerer to be able to start from. It sounds like you're making a claim that they're the same and then asking for someone to make a counterpoint, but you never provided your definition of
My best interpretation of your question is that it asks what the
umask command does, in which case it's a duplicate of Why doesn't umask change execute permissions on files? or How umask works or others. If you're unclear on how umask works, my suggestion would be to play with it on some test files, read the umask tagged questions, and then ask about a surprising or confusing result you had.
Your revised question, after un-doing the graffiti -- please don't deface your own questions, there's a delete link for the question, if you need it -- now reads in the same general, confusing way. You ask:
Are there any other important use cases of mask streams?
where you seem to make up the phrase "mask stream" by combining "bit stream" with "bitmask" and then asking an open-ended question about what they might be used for.
Ask an answerable question where you lay out what you know and where your knowledge ends (or surprise begins). Questions are free, so focus one Question on one question: if you want to know what how a umask is different from a mask, then define those two to your understanding and ask that; if you want to know what "mask streams" are used for, I'm not sure how to help you. It's hard to use someone else's definition and extrapolate it, and this site isn't geared towards open-ended questions.