I just rebuilt my motor with a used short block, does it still need a break in period?

Silly question, but whats the difference in a motor and an engine?

 

A motor is electrical with a stator and windings. An engine usually runs on a fuel, has combustion and inhales and exhales. I say usually cause a Carnaugh(spelling) engine comes to mind.

BTW if the bottom of the engine (your short block) was used and has no new parts, it does not require a break in period. However, it may not be a bad idea to check the major fasteners for torque value after a few days of use.