【Instance】 ,  【case】 ,  【illustration】 ,  【example】 ,  【sample】 ,  【specimen】  mean a concrete thing which has or manifests the qualities, characters, or nature of a type, a class, or a group.

【Instance】 applies to an individual person or thing brought forth in support or disproof of a general statement or as a means of indicating the character of a class.

【Case】 applies to an act, situation, condition, or event demonstrating the occurrence or the existence of something which is being considered, studied, investigated, or dealt with or exhibiting it in actual operation.

【Illustration】 applies to an 【instance】 adduced or cited as a means of throwing light upon what has been explained or discussed in general terms.

【Example】 (see also MODEL ) applies to a typical, representative, or illustrative 【instance】 or 【case】 .

A  【sample】 is a usually randomly selected part or unit of a whole presumed to be typical or representative of the whole from which it is taken.

【Specimen】  and  【sample】  are often used without distinction, but  【specimen】 is more often the choice when the whole is composed of discrete units that are independent entities.