Why to differ spindles from shafts?

they are generic names, and there isn't great difference between them


Spindle is actually a torque or power transmitting member only and does not support the weight of any driven member.

in short spindles are only subjected to torsion, and not bending moment.

the best example is that of a spindle in a food processor. the motor spindle only interlocks with the internal splines of the cutting blade, but does not support the blade as such.

Shaft on the other hand transmits power and also supports driven members such as pulleys,gears etc.