Both can produce the same models, it's just they have different features and difficulty levels. The free Gmax cannot compile models, while 3D Studio Max is the same, but has more features and is very expensive. Milkshape is easier to use and can compile models, but you have to buy it to keep using it after the 30 day trail expires, but it is much cheaper. It depends on what you can afford and what you are looking for in a program. It depends on how much patience you have and how much skill you have.