What are the difference between fan, blower, and compressor

The classification can be done according to dicharge pressure over the suction pressure ratio;-

For Fan - 1 to 1.1

For Blower - 1.1 to 3

For Compressor - 3 to 5

there is a term called specific volume.it is the reciprocal of density.

in case of fan or blower the specific volume almost remains constant, but in case of compressor the specific volume changes and the fluid(air) is compressed

Hello;

As you know fans and blowers provide air for ventillation and industrial process requirements.Fan blower and compressors are differentiated by the methode used to move the air , and by the systeme pressure they most operate against , according to the ASME ( American Society of Mechanical Engineers), the classification is done according to the discharge pressure over the suction pressure  ratio.

This ratio is up to1.11 for the Fan ,1.11 to1.20 for Blowers and rise to  more than1.20 for Compressors.