I always assumed that the green help links color was intentionally differentiated from regular blue web links to clearly imply that they remain within the "Help" universe.
The timeline might undermine my assumption.
The timeline might undermine my assumption.
At any rate, there wouldn't be any need to distinguish internal help links from web links, because neither Windows 3.0 nor 3.1 ever shipped with a web browser-- can't link out in your docs if the tools aren't available to follow the links. Early versions of Windows 95 didn't, either, with IE 2.0 being bundled with the OS for the first time with OSR1.