The key difference lies in the stage of adaptation. 'Be used to' describes a state of being accustomed to something, indicating that it is already familiar and comfortable. It's about the result of adaptation.
'Get used to' describes the process of becoming accustomed to something. It implies a transition from finding something strange or new to finding it familiar and comfortable. It's about the action or process of adapting.
In simpler terms: You get used to something (the process), and then you are used to it (the state of being accustomed).