Product:
Something produced by industrial and mechanical processes (e.g., a car, toaster,
elevator).
Component:
A single piece of a larger assembly (e.g. a shaft).
Part:
Not well defined. A constituent part of a product. It can also be a product in its own right (e.g. a gearbox).
Machine:
An assembly of linked parts or components with a drive system intended to undertake a
specific application.
Machine Element:
A basic mechanical part or component. Machine elements form the building
blocks of machines. Although they may be unique to an application, they are typically standardised to common sizes.
Bearings:
Bearings facilitate the transmission of loads,
whilst allowing relative motion.
Shafts:
A (usually) rotating component for the transmission of power.
Typically, of circular cross section, though there are obvious common exceptions.
Seals:
The purpose of a seal is to prevent or limit the flow of fluids (or passage of particles) in between two components.
Seals are of two general categories:
Gears:
Transmit power between shafts.
Many types, depending on relationship between axes.
Fasteners:
Fasteners join two or more components