How to strip version folder from Windows Boost build?

Question

I'm building Boost from source on linux and windows from a single python script, and notice the linux build places the headers under <prefix>/include/boost/..., whereas the windows builds add a version level <prefix>/include/boost-1_74/boost/.... Interestingly, this level does not appear for lib.

Running diff on both folders show no difference between them.

Looking at the .\b2.exe --help there is no mention of special behavior between windows and linux:

Targets and Related Options:

  install                 Install headers and compiled library files to the
  =======                 configured locations (below).

  --prefix=<PREFIX>       Install architecture independent files here.
                          Default: C:\Boost on Windows
                          Default: /usr/local on Unix, Linux, etc.

  --exec-prefix=<EPREFIX> Install architecture dependent files here.
                          Default: <PREFIX>

  --libdir=<LIBDIR>       Install library files here.
                          Default: <EPREFIX>/lib

  --includedir=<HDRDIR>   Install header files here.
                          Default: <PREFIX>/include

Where is this level coming from? How do I make it go away?