RHEL7 x86_64 contains modules Solaris x86_64 does not:

mod_cern_meta.so
mod_ident.so
mod_imagemap.so
mod_proxy_fdpass.so
mod_security2-jws3.so
mod_session_crypto.so
mod_systemd.so  (this is obviously O.K.)

Solaris x86_64 contains modules RHEL7 x86_64 does not:

mod_dialup.so
mod_echo.so

• Note that, for instance, Solaris contains var/www/manual/mod/mod_proxy_fdpass.html, while missing the *.so file itself.
• Please, note mod_security2-jws3.so absence is especially painful for it blocks our mod_security tests.