So what's the difference? 0777 Any user can read, write, execute, delete, rename the file vs 1777 Any user can read, write, execute, but cannot delete or rename the file unless they are the owner?

Similarly, 0777 Anyone in the group can read, write, execute, delete, rename the files vs 2777 Anyone in the group can read, write and execute but cannot delete or rename unless they own the files?

*Disclaimer Apparently there are different implementations of the rules across *nix/posix systems I'm just trying to wrap my head around the basic understanding of what it's for.

Bonus question: I assume you cannot have 1774/2744 or similar along those lines correct?