The real distinction is the basis of classification.
AspectScience introductionBook introduction
Relates toThe science and its questionsA particular written work
Key conditionNeeded to begin its problemsUseful text placed before the main content
ExampleA fundamental technical termThe book's chapter outline
The same discussion can qualify in both ways. The distinction depends on the perspective from which it is considered.
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Introduction: Structure, Three Disciplines and Kinds of Preface
The real distinction is the basis of classification.
AspectScience introductionBook introduction
Relates toThe science and its questionsA particular written work
Key conditionNeeded to begin its problemsUseful text placed before the main content
ExampleA fundamental technical termThe book's chapter outline
The same discussion can qualify in both ways. The distinction depends on the perspective from which it is considered.