What is the difference between switch --compile=yes & --compile=all for AOT?

Googling the option (and searching in the Docs) found this:

https://github.com/JuliaLang/julia/issues/23054

[and nothing of interest in Docs; as the option has been hidden in master.]

https://github.com/JuliaLang/julia/blob/master/src/jloptions.c

https://github.com/JuliaLang/julia/issues/15864