what is meaning of going to be a and how to use.

"Going to be" means होने जा रहा है/ बनने जा रहा है It is used in those types of sentences which give the sense of future time. Ex:- I am going to be an engineer. मैं एक इंजीनियर बनने जा रही हूं/ मैं एक इंजीनियर बनने वाली हूं

what is the difference between going to and going to be?