Hi Lambsie,
The holding speed put simply is an endurance speed, it gives you close to the minimum kg/hr, minimum thrust and drag are required. The best endurance speed is where the drag is least.
The maximum range speed would give us the maximum nm per kg. This speed is higher than the endurance speed. We are looking for the highest IAS for the least drag, or thrust, or fuel consumption. This would then give us the maximum range. Close to Vmd, but not quite.
