For that particular product line, yes. All share same B8 chassis, safety features, AWD drivetrain (everything past transfer case), and most interior, body panels, etc. The different first letter of the model name (A4, S4, RS4) is based on the performance level of the car and associated model specific features.
If we are going to keep using car analogies, Intel does the same thing in a way except with the suffix and prefix swapped.
Audi has RS4, S4, A4
Intel has i5-2500K, i5-2500, i5-2500S, i5-2500T