Difference between TMPDIR environment variable, --workdir in Toil / CWL

Question

[ionox0]

I was wondering whether anyone could explain the difference between the TMPDIR environment variable that is used by cwltool and the --workDir parameter that is used by Toil.

Which is used for what purpose, and will one override the other when using Toil 3.15?

If this question could use some additional clarification from my end please let me know.

Thank you!