I agree that you will find many differences between the sim and the trainer... If you are new to this hobby - do get the sim... The sim will allow you to practice the 'concepts' of rc flight. What I mean is that you will not be able to choose a plane on the sim, build the same plane and fly it the same... it doesn't work like that.

But what the sim will do for you is allow you to practice these concepts of rc flight. For example you will become familar with inverted flight and the coordination needed to fly towards you vs. away. The sim is a great begining tool.