Settings windows different colors?

I noticed that some windows have a different, more basic appearance that others. I particular the Studio setup and VST connections screens have a very basic black and white layout. Does this have to do with the fact that I am running Mac OS Sierra? (unable to upgrade to Mojave at this moment).

The attached screenshots show the window on my Sierra system and on my colleague’s Mojave system. Can someone explain?


Or does this have to do with “Dark mode” vs “Light mode” which can be changed from High Sierra / Mojave, but not on Sierra?

It has to do with the fact that those windows have not been updated for years - updates are long overdue.