one of a number, part of a whole, used to show what the rest is like

example, model

one of the parts into which something has or may be divided; one of a number of parts which can be put together to make a structure

division, portion

one used as an example; a part taken to represent the whole

example, sample

the state of not being the same, or not being the same at all times; a number or range of different things; a subdivision of a species

difference