Sample and Instance

sample

A small part of something intended as representative of the whole.
Items selected at random from a population and used to test hypotheses about the population.
- synonyms: sample distribution, sampling
All or part of a natural object that is collected and preserved as an example of its class.

Take a sample of.
- usage: "Try these new crackers"; "Sample the regional dishes"
- synonyms: try, try out, taste

(n.) Example; pattern.
(v.t.) To make or show something similar to; to match.
(v.t.) To take or to test a sample or samples of; as, to sample sugar, teas, wools, cloths.
(n.) A part of anything presented for inspection or shown as evidence of the quality of the whole; a specimen; as, goods are often purchased by samples.

Webster's Revised Unabridged Dictionary

instance

An occurrence of something.
- usage: "it was a case of bad judgment"; "another instance occurred yesterday"; "but there is always the famous example of the Smiths"
- synonyms: case, example
An item of information that is typical of a class or group.
- usage: "this patient provides a typical example of the syndrome"; "there is an example on page 10"
- synonyms: example, illustration, representative

(n.) That which is instant or urgent; motive.
(n.) That which offers itself or is offered as an illustrative case; something cited in proof or exemplification; a case occurring; an example.
(n.) Occasion; order of occurrence.
(n.) The act or quality of being instant or pressing; urgency; solicitation; application; suggestion; motion.
(v.t.) To mention as a case or example; to refer to; to cite; as, to instance a fact.
(n.) A token; a sign; a symptom or indication.
(v.i.) To give an example.

Webster's Revised Unabridged Dictionary