The document discusses the difference between content words and function words. Content words, such as nouns, verbs, adjectives and adverbs, carry meaning in a sentence. Function words, such as articles, pronouns and conjunctions, provide grammatical structure but have little semantic meaning. While a clear distinction can be difficult to draw, content words generally add meaning and can change form with affixes, whereas function words maintain a consistent form and help the sentence function syntactically. The document provides examples to illustrate the differences between content and function words.