difference between Recovery Manager for AD (standard?) and RMAD FE

Hello!  I'm trying to understand how the licensing of RMAD works.

  • Is Forest Edition an add-on to RMAD?  In other words, do I need RMAD as a base license to install RMAD FE?
  • If not, does it make sense to own both products?

Very confusing and I can't find an explanation anywhere.  Appreciate any insight that can be shared, thanks!