[Gone4]

There is generally a difference in rotors but the primary problem with using an AC induction motor as a BLDC is that a BLDC has integrated controls that include an absolute position sensor, required for the digital controller to properly power the motor so it spins. Also, for many reasons, BLDC motors uses permanent magnets, which you lose some power over by not being able to manipulate the magnetic (B) field whereas AC motors have a magnetic (B) field proportional to voltage and frequency. You can take away from this vague response that this also correctly implies that BLDC are more efficient for smaller motors but experience more losses as you scale the design up, so AC induction becomes more efficient for higher performance applications.

The reasons for these differences get complex, so I assume this will suffice. They may seem the same, but they are not easily interchangeable.