What is RTOW and how is it different from MTOW?
Google gives you the answer without even clicking any links:

https://www.google.com/search?q=RTOW


  MTOW is a hard limit regardless of other considerations and is tied up
  with the basic aircraft certification basis.RTOW is the limiting
  takeoff weight calculated for a particular runway under particular
  specified conditions


Maximum Take Off Weight - The maximum weight in which an aircraft can ever take-off, under any circumstances.

Regulated Take Off Weight - The maximum weight in which an aircraft can take off from a particular runway under specific conditions (winds, weather, specific aircraft configuration, etc,). For example, runway 29 at KXYZ airport with ambient temp of 20° C. This can get as specific as you wish.

Of course $RTOW \le MTOW$.