One physical motor can carry all three kinds of number. The equipment maker lists it under a service part number and identifies it by the number on its nameplate. The motor maker publishes its specifications under a catalog number.

Maker's catalog numberthis page

The number the motor maker sells the motor under, such as Fasco D1245. Its specifications are published in full. Equipment makers do not list fitments against it.

Service part number

The number an equipment maker prints in its own parts list, such as Trenton 1109057. It says which units the part is fitted to, and nothing about the part itself.

Nameplate number

The number on the motor's own nameplate, such as Genteq 5SME39HLHF412C. The motor maker builds it to the equipment maker's order, so its full specification is rarely published.